List of popular psychological experiments!
Experiments on Attention:
1. Division of Attention:
The question whether our attention can be divided between two or more things or jobs at the same time has been studied by many experimenters. These studies have taken the form of requiring the subjects to perform the tasks separately and then simultaneously. In studying this problem the nature of the task must be kept in mind.
The two tasks may be physical or motor, intellectual or mental or one task may be mental and the other may be physical. In general, the loss of efficiency in physical tasks has been found to decrease with time because both the physical tasks become automatic and probably there is little attention involved in either or both of them after practice.
To verify the hypothesis that efficiency of work or attention decreases when two tasks are performed at the same time.
The division of attention board or Mc Dougall’s disc apparatus, and two mental tasks. For the present experiment, the division of attention board can be used for both the mental tasks- (1) writing every fourth number starting from 1 and (2) speaking out every third alphabet starting from A.
The apparatus consists of a wooden board with a circular and triangular groove with a metallic contact point on each. The board is wired so that any passage of electric current on it from a battery can be recorded on an impulse counter.
The board is connected to a battery terminal. The other terminal of the battery is connected to a metallic stylus through an impulse counter. Whenever the stylus touches the metallic contact point, the impulse counter records it as one error.
The experiment consists of three series, namely:
(i) Two physical tasks,
(ii) Two mental tasks, and
(iii) One physical and one mental task.
1. Ask the subject to trace the circular groove with his left hand for a period of two minutes and note the number of errors recorded in the impulse counter (S1).
2. Ask the subject to trace the triangular groove with his right hand for a period of two minutes and record the number of errors recorded in the impulse counter (S2).
3. Ask the subject to trace the circular groove with the left hand and the triangular groove with the right hand simultaneously for two minutes. Record the total number of errors (D1 & D2).
Calculate the co-efficient of division of attention as follows:
Coefficient of division of attention C.D = (D1 + D2)/(S1 + S2)
S1 = Score on first physical task done individually;
S2 = Score on second physical task done individually;
D1 = Score on the first task done along with the second task;
D2 = Score on the second task when carried out along with the first task.
If the efficiency is affected by the division of attention between two tasks, then the coefficient will be less than one.
1. Ask the subject to write down every fourth number starting from 1(one) on a piece of paper. Ask him to stop at the end of 2 minutes. Correct the numbers and count the number of correct responses (S1).
2. This time ask him to call out every third letter starting from ‘A’. When he comes to ‘Z’ ask him to continue backwards through ‘A’. Stop after two minutes again and count the number of correct responses (S2).
3. Now ask the subject to write down every fourth number and speak out every third letter at the same time for two minutes. Count the numbers correctly written (D1) and the number of alphabets correctly spelt (D2).
4. Calculate the coefficient of division of attention as before.
This set includes one mental task and one physical task. Since the data for individual performance of a physical task and a mental task are already available under Series I and II, this part consists of only one step.
Ask the subject to trace the circular groove with his left hand and write down every fourth number at the same time for 2 minutes. Calculate the C.D.
Compare the coefficient of the division of attention under all the 3 series.
Tabulate the group results as follows:
1. Calculate the Mean and Standard Deviation and study the individual variation.
2. In which series is the coefficient highest and in which the lowest for the group.
3. Do all individuals conform to this order?
This experiment is useful in arranging tasks in a work situation so that the division of attention may be minimised.
2. Fluctuation of Attention:
Whenever we are attending to certain stimuli, our sensory experiences do not remain the same. Our attention fluctuates from one part of the stimulus to another and also goes up and down in efficiency. This takes place even if the stimulus remains stationary and without any change. These shifts and fluctuations are entirely due to internal conditions.
To demonstrate the phenomenon of fluctuation of attention.
Mason’s disc- a colour wheel, a Kymograph with accessories, time markers, smoke paper, burner.
The Mason’s disc consists of a circular cardboard or plastic disc with a hole in the middle, for the purpose of fitting it to the colour wheel. Along one of the diameters of this circle there are a series of small black squares. When the disc rotates on the colour wheel, these produce a series of grey rings. These rings become fainter and fainter as one proceeds from the centre to the periphery. The subject has to choose the least clear of these circle and fixate on it while the disc rotates.
The Kymograph with a smoke paper pasted to it is adjusted to rotate at the rate of 15 to 20 revolutions per minute. The electromagnetic marker or stylus is fixed on an adjacent stand in such a way that it is in contact with the smoke paper as the Kymograph rotates. The electrical connections are passed through a commutator and a push key.
The Mason’s disc is fixed to the colour wheel placed in front of a screen. It is rotated and the subject is given a few practice trials to enable him to select the faintest circle and fixate on it.
The following instructions are given:
“As soon as I say ‘ready’, keep your finger on the push key and also close your eyes. When I say ‘begin’ open your eyes and keep looking at the faintest ring on this wheel. Concentrate on the ring and press the key. After sometime this ring will disappear. Then press the key again. Like this go on pressing the key every time the faintest ring appears and disappears until I ask you to stop.”
Start the colour wheel and say ‘ready’. Switch on the Kymograph and record the responses for a period of 3 minutes.
Lower the height of the Kymograph and take one more set of readings.
1. With the help of a time-marker, measure the length of time interval between successive sets of appearances and disappearances.
2. Note the time interval between successive sets of disappearances and appearances.
3. Study how the stimulus appears and disappears during the course of the observation.
Experiments on Sensation:
3. Chemical Sensations:
Of the eight different basic sensations, the gustatory and the olfactory senses together are called chemical senses. This is because experience of these sensations depends on chemical changes which take place when the respective receptors come into contact with the stimuli. This is not the case with visual, auditory or actual stimuli.
Comparatively speaking, much less has been understood of these senses. It is common experience that often the sensation of taste and smell go together. In fact, in many instances it is accompanied by cutaneous sensitivity.
To study the sensitivity of different areas of the tongue to different taste stimuli.
Solutions of sugar, sour buttermilk and quinine, a glass rod, an ink filler and a blind folder.
Make an outline of the tongue on a sheet of paper.
Blindfold the subject and give him the following instructions:
I will put a few drops of different solutions on your tongue. After I put each drop, tell me how it tastes’. Take a drop of the sugar solution with the ink filler or the glass rod and drop it on a point at the tip of the tongue. Note the response. Note the point and response on the sheet of the paper. Similarly place the drops of the sugar solution on points in the middle of the tongue at the back of the tongue and at the two sides. Note down the responses. After this wipe the tongue with a clean towel.
Repeat the experiment with solutions of salt, quinine and buttermilk, each time making a note of the stimulated point and the response on the outline.
Repeat the experiment with combinations of sweet and salty, sweet and bitter solutions etc.
Tabulate the results as follows:
See whether the different areas of the tongue are different in their sensitivity to different tastes.
4. Determining the Two-Point Threshold:
To determine the minimum distance necessary for a subject to feel two different sensations when two points on the skin are stimulated simultaneously. This minimum distance is the two-point threshold.
A compass aesthesiometer. It consists of two points, the distance between which can be adjusted by means of a screw arrangement. There is a scale arrangement by which the distance between the two can be measured. When the two points are kept very close and the subject is touched with both the points, he experiences only one touch and not two. But, if the distance between the two points is increased to a minimum degree, he experiences two stimulations. All distances beyond this minimum degree produce two sensations.
The subject is blindfolded throughout the course of the experiment. This experiment is also done in two series, ascending and descending. In the ascending series the experimenter starts with the two points of the aesthesiometer placing it in such a manner that the subject reports that only one point is being touched.
Then the distance is gradually increased by one millimeter each time until on three consecutive occasions the subject reports having been touched at two places. The two point threshold is given by the reading on the scale corresponding to the first of these three ‘two’ responses.
In the descending series, the experimenter starts with the ‘two’ points wide apart and the subject reports that he feels the two stimulations. The distance is gradually decreased by a millimeter each time until the subject reports on three consecutive occasions an experience of ‘one’ stimulation only. The threshold value corresponds to the first of these three ‘one’ responses.
Tabulate the results as follows:
4. Discuss the variations among the member’s responses. See whether there is any significant difference between the two series.
i. With the help of a few preliminary trials, the lower limit (below which, the subject always reports one point) and the upper limit (above which, the subject always reports two points) of the ascending and the descending series are to be determined. This is necessary to avoid undue trial lengths of each series.
ii. To avoid a ‘response set’ on the part of the subject, the starting point of each trial should be varied randomly.
5. Olfactory Adaptation:
To demonstrate the phenomenon of sensory adaptation and differential rates of adaptation for different odours.
Four bottles of odoriferous substances. Bottles A, B and C contain solutions of single odour while bottle ‘D’ contains combination of these three odours.
Ask the subject to smell the substance in bottle ‘D’ and report when he ceases to experience the odour. Record the time in seconds. Ask him whether he can identify the various objects which might produce that smell. After an interval of a few minutes repeat the procedure five times. After the five trials allow a ten minutes break. Note down the adaptation time for the five trials.
Repeat the experiment with the other three bottles. After you have finished with the three bottles ask the subject to smell solution ‘D’ again and find out whether he is able to identify the components.
Tabulate the results as follows:
a. Compare the adaptation time for the different odours.
b. Does it change with practice?
c. Compare the adaptation time for the individual odours with that for the combination of odours.
d. Does experience with A, B and C lead to easier identification of the components of ‘D’? This can be found out by comparing the subject’s identification of the components of D before and after smelling the individual odours.
e. Collect the group data and tabulate it as follows:
Experiments on Perception:
The word subliminal comes from Limen, which means threshold. Any stimulus can be varied to the point where it is so weak or so brief that it cannot be perceived. When this happens it is said to be subliminal. Experiments have suggested that although a person does not consciously perceive a stimulus, s/he may nevertheless be influenced by it.
For example, a claim was made that, flashing subliminally at repeated intervals the words ‘Eat popcorn’ and ‘Drink Coca – Cola’ on the screen in a movie theatre, led to substantial increase in the sale of popcorn and Coca-Cola. Subliminal perception does not mean that people respond to stimulation below the awareness threshold but that they can respond to stimuli which, for one reason or another, they are unaware of.
Subliminal perception has practical importance not only in advertising but also in understanding the principle underlying certain types of behaviour. Freud and other analysts place great stress upon the importance of unconscious processes in behaviour dynamic. Hundreds of experiments relevant to the problem of subliminal perception have been conducted in psychophysics and in the study of “Extrasensory Perception”, commonly known as E.S.P.
The study of Smith and Hennikson involved the tachistoscopic exposure of two stimuli. The first exposure consisted of fan-shaped array of lines presented below the awareness threshold. This was immediately followed by the presentation of clearly perceptible sets of shapes that closely correspond to what they had already seen.
A number of experiments which have been compiled on subliminal perception demonstrate the remarkable capacity of the human organism for responding to partial information contained in subliminal stimuli.
To study the phenomenon of subliminal perception of visual stimuli.
A set of cards with designs given in Figures I and II tachistoscope.
Description of Cards:
Set A- Consists of 10 cards with different geometrical designs. Each design depicted with an array of lines.
Set B- Consists of 15 cards, with geometrical designs drawn in single line. Out of these, 10 designs correspond to designs of Set A and 5 designs do not correspond.
The subject is seated comfortably before the tachistoscope.
The following instructions are given:
“Watch carefully. I shall present a figure to you for a brief moment”. After presenting one card from Set A, for less than 1/10 of a second, the subject is instructed once again- “Now, I shall present to you some designs one after the other. Tell me, or note down on this paper as to which design is similar to the figure which you have seen previously”. All the cards of Set B are presented one after the other, each card is exposed for 3 seconds.
The presentation of each card from Set A, is followed by the presentation of the cards of set B. The above procedure is repeated until all the cards of Set A are exposed.
The number and percentage of correct individual and group responses indicate the presence of subliminal perception.
Perception is an active process by means of which we select, organize and give meaning to the information which we receive from both external and internal sources. For good or evil, our motives exercise a continuing influence over how we perceive and what we perceive. Firstly, we are more sensitive to information related to our needs and desires. Secondly, we try to screen off information that would make us uncomfortable. The latter process wherein one actively resists certain perceptions is referred to as “perceptual defence”.
Numerous studies reveal three basic processes involved in perceptual defence. These processes were successfully demonstrated by McGinnie.
(1) Emotionally disturbing, threatening or critical stimuli have a higher recognition threshold than neutral stimuli.
(2) Emotionally threatening stimuli are likely to elicit or substitute perceptions that are totally different, so as to prevent recognisation of presented stimuli.
(3) Critical stimuli arouse emotional reactions even though the stimuli are not recognized.
Perceptual defence may also depend upon a person’s culture, past experience and knowledge. The student familiar with the psychoanalytic theory will recognize similarities between perceptual defence mechanisms and the distortions of thought processes, such as the substitution of an innocent symbol for an anxiety laden object in a dream.
To determine the phenomenon of perceptual defence.
A set of 18 pictures. Set ‘A’ consisting of 11 pictures which are neutral in content, like a tree, a building, a radio etc. Set ‘B’ consisting of 7 pictures which are of obscene quality, depicting a nude female or male figure, the female bosom, etc. Tachistoscope, Stopwatch, G.S.R. apparatus.
The subject is seated comfortably in front of the tachistoscope. Points of the G.S.R. apparatus have to be fixed at appropriate spots.
Then give the following instructions:
“I shall present a set of pictures one after the other. Each picture will be exposed for a fraction of a second, tell me what you see”.
The pictures of both sets are shuffled. The experimenter gives a ‘ready’ signal before presenting the picture to the subject. Each picture is exposed for 1/10 of a second. After exposing a picture, the experimenter notes down the time taken by the subject to report what he has seen.
The response to each picture, either right or wrong is noted down. G.S.R. measures are recorded automatically. In the absence of the G.S.R apparatus the experimenter interviews the subject after the completion of the experiment to find out if any picture had provoked anxiety and emotional changes in the subject, and records the answers carefully.
(1) The experiment should be conducted as an individual experiment.
(2) To avoid inhibitions, adequate rapport with the subject should be established by the experimenter.
(3) The experimenter should ascertain that emotional changes have taken place before noting them down.
Tabulate the results as follows:
Individual results, i.e. time taken, number of similar and dissimilar responses, and G.S.R. measures of both neutral and critical pictures are compared.
Individual results are compared with group results.
8. Suggestion by Progressive Weights:
Our perceptions and judgement are not always based on direct effects of stimulation. Often, many factors around a stimulus tend to influence our perception and judgement. Likewise, in many instances we accept the opinion and reactions of others without critically examining them. This process of responding uncritically to a stimulus situation is known as suggestion. People respond to suggestion from social as well as non-social factors.
To demonstrate the occurrence of suggestion in a non-social situation.
A box of weights consisting of a number of cubes which vary in size as well as Wight. However, some of the smaller cubes are actually heavier than some of the larger ones. Some cubes though varying in size are actually equal in weight. The cubes are arranged in the box from the smallest to the largest in order of size. The first few cubes, however, vary progressively in weight as well as in size.
Give the following instructions to the subjects:
“You will see a number of cubes in this box I will place them one by one on your palm. As soon as I place the second cube, tell me whether it is lighter or heavier than or equal to the first one. After this, each time I place a cube tell me whether the particular cube is lighter or heavier than the previous one.”
The experimenter places the cubes one by one on the subject’s right palm. Each time he notes the response of the subject as heavier, lighter or equal. After all the cubes have been placed on the subject’s “palm, they are weighed individually with the help of a balance. The subject’s responses are checked against the weights. The number of wrong responses are recorded.
Wrong responses fall into the following categories:
1. Larger but lighter cubes in the series being judged as heavier,
2. Smaller but heavier cubes being judged as lighter, and
3. Cubes with the same weight as the preceding one being judged as heavier or lighter. These wrong responses are due to the influence of suggestion.
Tabulate the number of suggestions accepted by the entire group as follows:
Calculate the mean and study the variability by estimating SD.
Experiments on Suggestibility:
9. Illusion of Warmth:
To demonstrate the process of suggestion operating in cutaneous sensation.
Illusion of Warmth Box. This box consists of a coil of wires and four lamps connected in a series. On the box, by the side of the lamp there is a switch to light the lamps as well as to get the coil heated. Whenever the lamps are switched on, the coil gets heated. Inside the box, however is a concealed switch by operating which the coil can be cut off from the circuit so that it does not get heated even if the lamps are burning.
1. The subject is instructed to hold the coil with his right hand and asked to report whenever he feels the heat. He is told that whenever the lights burn the coil will get heated.
2. The experimenter demonstrates by switching on the circuit of the box.
3. The experimenter prepares a list of 40 trials. Out of these. 20 are normal trials where the coil is also linked to the circuit while the other 20 are suggestive trials in which the coil is cut off the circuit by operating the concealed switch. The trials, normal and suggestive, are randomised. However, the first few trials should be normal trials where the coil actually gets heated.
4. The experimenter presents the 40 trials and asks the subject to report when he feels the heat. In between each trial, however, a rest period of 3 minutes is allowed.
Note the number of suggestive trials when the subject actually reports feeling the heat. Tabulate the results as follows:
1. Calculate the Mean and the Standard Deviation and discuss individual variations.
2. Correlate the suggestibility in this experiment with the suggestibility in the experiment on progressive weights.
3. Is suggestibility a general trait?
10. Suggestibility in Testimony:
To study individual differences in susceptibility to suggestion, while offering testimony.
A set of articles of everyday life, like a postage stamp, penknife, and a picture calendar mounted on a single board with a cover.
A list of questions pertaining to these objects, about 5 to 6 on each object. Out of these questions for each object, three should be of a suggestive nature.
For a knife- Did you see a black spot on the handle of the knife?
1. The subjects are instructed as follows- ‘On this board are placed a number of objects. I will show them to you for a brief time. Take a good look at them. I will then ask you some questions about them, which you will have to answer.’
2. Small groups of subjects, not exceeding three at a time are shown the articles for a very short duration, about 30 seconds. The procedure is repeated until all the subjects have look.
Then a sheet containing the questions is handed over to each subject and s/he is required to answer the questions.
1. Analyse the answers to the suggestive questions. Find out how many of the false suggestions are accepted. Tabulate results as in the previous experiment. Calculate the mean for the group and study the individual differences.
2. Compare the mean of the correct responses for the suggestive and non-suggestive questions and test the significance of the differences.
3. Analyse the number of suggestions accepted by the entire group for the different objects. Find out which object lends itself best to suggestion.
Experiments on Feeling and Emotions:
11. Strength of Motives:
The human organism behaves differently in different situations because such behaviour leads to a satisfaction of one or the other of many motives. There are different types of basic motives in the human organism, like hunger, sex, thirst, security, etc. Some of these motives are stronger than the other motives.
The comparative strengths of different motives vary from individual to individual, depending on the physiological conditions like age, past experience, etc. Attempts have been made using the association technique to compare the strengths of different common motives. These results have shown the influence of the different factors mentioned above on the comparative strengths of different motives.
To determine the comparative strength of hunger, thirst and sex motives through the association technique.
A list of 30 words consisting of ten words each pertaining to each of the three motives, and a stopwatch.
Instruct the subject as follows:
1. “I will be calling out a number of words one after the other. As soon as I call out a particular word you will have to respond with the first word which occurs to you. Do not think about the responses. Speak out the very first word which occurs to you or comes to your mind after hearing the word I utter “. The experimenter takes a few other neutral words and gives a few demonstrations trials. Before reading out each word, a “ready” signal must be given.
2. The experimenter reads out the first word and at the same time starts the stopwatch. As soon as the subject gives the response, the time is noted down and also the response word. The procedure is repeated with all the 30 words. The 30 words are read out in a random order.
1. Calculate the average reaction time for the three groups of words belonging to the three motives.
2. Analyse the responses for words of each motive and find out how many out of the total number of responses are “motive-connected” responses for each group of ten words. ‘Motive-connected’ responses are those which appear to be connected with the particular motive meant to be aroused by the stimulus.
3. Tabulate the results for the entire class as follows:
4. Compare the average action time for the three groups. The stronger the motive, the lesser the reaction time will be. Test the significance of the differences.
5. Compare the number of motive-connected responses, the stronger the motive the more will be the number of motive connected responses.
However, it has been shown by psychoanalysts that if certain motives become particularly strong they tend to get suppressed in the process of expression. In such instances reaction time may be very long and the number of ‘motive-connected’ responses may be very low.
It is often said that the face is the index of a man. This statement implies that the emotions, feelings and mental states of individuals can be judged from the expressions on their faces. This generalisation was put to experimental study first by Charles Darwin and later on by Piderit. On the basis of certain simple and crude experiments, Piderit arrived at the conclusion that judgement of emotion from facial expression is not always possible. Similar results were arrived at by Titchner, Fenburger and others.
To study the ability of an individual to judge the emotions depicted in a photograph.
A set of Ruckmik’s pictures and the corresponding list of emotions depicted by them. Ruckmik’s pictures consist of 18 pictures depicting different emotions.
1. Place the pictures one after the other in quick succession before the subject and ask him or her to describe the specific emotion depicted in the picture. When the subject has seen all 18 pictures, collect the subject’s responses and check them with the correct list.
2. Now place all the 18 pictures before the subject and also the list of emotions, in a jumbled order. Ask him to match each emotion in the list with each photograph. Correct the responses.
Tabulate the results for the entire class as follows:
1. Study the average success and the variability. Compare the two series.
2. Collect an introspective report from the subject. Analyse it and find out the features which he has used as cues in judging the emotions.
3. Tabulate the frequency for the different features for the entire class.
Experiment on Reaction Time:
13. Choice Reaction Time:
To determine the choice reaction time, i.e., the time taken to respond when the subject has to discriminate between stimuli and also choose different responses for different stimuli.
The procedure is more or less the same as the one for the discrimination reaction time experiment. The same 40 stimuli are used but the instructions are as follows- “Again you will see on different occasions a white or a red light burning. Whenever you see a red light, you have to press the left key. However, you always must use the right hand to press the key. On the other hand, if you see a white light, you must press the right key with your left hand.”
As before, the trials are given and the average reaction time is recorded. Again, two auditory stimuli may be used in the place of the visual stimuli.
Tabulate the results for the entire class:
Calculate the Mean Average and the SD and discuss the variability.
Comparison of the 3 types of reaction time.
Tabulate the results for the three types of reaction time as follows:
1. Compare the means of the three types of reaction time for the same type of stimulus and test the significance of difference.
2. Compare the two different sense modalities for each type of reaction time and test the significance of difference.
The Reaction time offers a very useful measure to select people for jobs requiring quick reaction time. Comparative data on reaction time for different types of stimuli helps to determine the most effective types of signal for different situations. Such studies also help us to estimate the time required to respond to traffic signals.
Experiments on Fatigue:
14. Muscular Fatigue:
To demonstrate the onset of fatigue as a result of continuous work, and also to demonstrate the influence of rest interval.
Ergograph, Kymograph, Recording tambour, weights, Metronome.
Description of the Ergograph:
The ergograph is simple apparatus, which consists of a pulley at one end over which passes a thick nylon string, at the end of which are suspended some weights, totalling to say about ten pounds. At the other end, the string ends in a small loop. In between there is a spring and lever arrangement.
If a subject pulls the loop the weight move up and down. The movements are recorded on a counter by means of the spring and lever arrangement. The actual extent of each pull can also be recorded on a rotating Kymographic drum by means of a marker. This will give us a continuous record of the extent of the pulls.
The subject is seated comfortably on the loop side of the ergograph and is asked to hold the loop with the index finger of the right hand while the other fingers hold a peg nearby (bolt-hand grip). A metronome is also set to work at the rate of 60 beats per minute.
The subject is given the following instructions:
“As soon as I say ‘ready’ start pulling at this loop. Go on doing this until I say ‘stop’. While pulling it you should be careful to keep pace with the beats of the metronome, i.e., you should pull whenever the pointer at the metronome comes to you and release the weight whenever it starts moving away.”
The experimenter gives a few practice trials. He/she says ‘ready’ and at the same time switches on the Kymograph also with a smoked paper already on it. At the same time, he also starts the stopwatch. At the end of every 30 seconds, he notes the reading in the counter. At the end of 5 minutes the subject is asked to stop pulling the string.
Remove the smoked paper carefully and wash it in shellac and then dry it. Study the changes in the curve. Compare the heights from the base line during the beginning of the experiment period and at the end. Calculate the work output in terms of ‘ergs’.
Effect of Rest Interval on Fatigue Level:
The procedure is essentially the same as in the earlier experiment excepting that at the end of every 2 1/2 minutes period of work, a one minute rest period is introduced. Again collect the data as before and study them.
Compare the reduction in work output under the two conditions with and without rest. You will find that if ‘rest’ is introduced the reduction, if at all it is there, will be much less.
15. The Effect of Nature of Work on Work Output Problem:
To study the difference in the extent and nature of reduction in work output in doing stereotyped jobs and when doing meaningful jobs.
A vowel cancellation list and a long list of arithmetical problems.
A vowel cancellation list is given to the subject and he is asked to go on cancelling the ‘A’s and ‘I’ s which he comes across. Instruct him that every time you call out ‘space’ he has to skip two lines and start working again.
The experimenter says ‘ready’ and starts the stopwatch. At the end of every one minute, he calls out ‘space’. This procedure is continued for a period of 10 minutes.
Now, the list of mathematical problems is handed over to the subject and he is asked to go on solving the problems. He is further instructed that whenever the experimenter says ‘line’ he has to draw a ‘line’ under the particular problem he is solving. Experimenter starts the stopwatch and at the end of every minute calls out ‘line’. The experiment is continued for 10 minutes.
The number of vowels cancelled and the number of problems solved for the successive one minute periods are tabulated. Two separate work curves are drawn for the vowels cancelled and the problems solved.
It will be noticed that the effect of fatigue sets in much earlier in monotonous jobs and also that the fall in work output of the work will be shaper.
If the subject is informed earlier that he will have to work for only ten minutes it will be found that towards the end of the 10 minutes period there is a spurt in the work output. The work curve suddenly goes up towards the end. This is called the ‘end spurt’.
Experiments on Learning:
16. Massed Vs. Spaced Learning:
A closely related problem in the psychology of learning has been massed vs. spaced learning. Is it better to tackle the learning material as a whole at the same time without having any rest intervals between successive readings or is it better to distribute the learning periods with rest periods in between? In a very early experiment on learning nonsense syllables, Ebbinghaus found the spaced method to be definitely better.
Pyle and Lashely arrived at the same conclusion when it came to learning type-writing and archery. Snoddy and later on Lorge got the same results in mirror drawing and mirror reading experiments. Similar results on animals have also been reported by Yerkes in experiments on animals. Peron found that up to a certain extent efficiency of learning increased with the length of the rest interval. On the whole, most of the experiments have produced results favorable to the spaced method.
To estimate the comparative merits of massed and spaced learning for verbal material.
A list of nonsense syllables and a memory drum.
The list of nonsense syllables may have about ten nonsense syllables, each of five letters. The memory drum consists of a rotating cylinder operated by a motor. The speed of this can be adjusted with the help of a gear. Over the drum is a curved metallic screen, concealing the drum from outside vision. In the middle of the screen there is a small window opening, which allows the view of a small portion of the drum inside.
When the list of nonsense syllables is pasted to the rotating drum, and the drum is switched on, the window allows a convenient vision of one syllable at a time. The syllables on the list should be written sufficiently largely and also spaced apart adequately to provide some interval between the exposure of the one word and the exposure of the next. The list is pasted and the gear is adjusted to give an optimal speed of rotation.
This experiment is once again a group experiment. Two matched groups are selected, one for the massed and other for the spaced method. However, the experiment itself has to be done individually on each subject.
A. Procedure for the Massed Learning:
Instruction to the Subject:
‘Look through this window opening (point out). You will see some syllables appearing through it one at a time. The drum will go on rotating and the same syllables will be appearing and reappearing, on the whole appearing for five times. At the end of this, you will have to reproduce the syllables.’ The experimenter says ‘ready’ and switches on the drum and allows it to rotate until the entire list has been exposed five times. At the end of this, the subject is asked to write down the syllables.
B. Procedure for Spaced Learning:
Here the procedure is the same accepting that the experimenter gives a rest of three to five minutes after every complete exposure of the list. The memory drum is stopped after all the syllables have been exposed once. After three to five minutes of rest, it is again switched on. Like this five presentations are gone through.
Tabulate the results as follows:
Test the significance of difference between the two by using the t-test.
Repeat the experiment with meaningful passages. Here, of course, the memory drum is not used. Instead, the passages can be read out five times to one group interspersing the readings with rest intervals and to the other group without the rest intervals.
The results of this experiment take on a special significance for students especially at the time of preparing for the examinations. It shows the futility of trying to learn a whole lot of things in a very short time.
17. Meaningful Vs. Rote Learning:
One of the questions which arise in the psychology of learning is whether the meaningful nature of a material makes any difference in the effort required to learn the given material. Experimental results have conclusively shown that subjects always find it easier to learn materials which appear meaningful to them. This is because meaningful material lends itself to the formation of better associations.
To compare the speed of learning for meaningful and meaningless materials.
A list of nonsense syllables consisting of ten syllables, five letters each. A corresponding list of meaningful words with ten words, each made up of five letters and a memory drum.
1. Paste the list of nonsense syllables on to the memory drum and adjust the drum to rotate at a suitable speed.
Give the following instructions- “Observe through the opening in the screen carefully. You will find a list of words appearing one after the other. These are words from a foreign language. These words will appear one after the other. You must learn these words by heart. Later on you will have to reproduce the entire list of the words. The list will be exposed to you as many times as you want.”
2. The list of words is exposed as many times as necessary until the subject is able to learn the complete list and reproduce it without committing mistakes. Remember that always the entire list has to be exposed and not any single word in particular. An exposure means the exposure of the complete list once.
3. Keep count of the number of exposures required by the subject. Stop the exposure when the subject is able to reproduce the list without a mistake. Repeat the procedure with the list of meaningful words, substituting in the instructions the term ‘familiar words’ instead of ‘syllables from a foreign language’. Count the number of exposures needed to learn this list
Tabulate the results for the entire class as follows:
Experiments on Remembering:
The process of memory includes encoding, storage and retrieval. One of the commonly used procedures for studying memory is free recall. In this, the subject’s task is to recall items in any order. Experimental evidence has shown that the level of recall was the highest for the words that had been presented at the beginning and at the end of the list.
Glanzer & Cunitz called this outcome as- “serial position effect” because the retention of an item depends upon the position in which the item had been presented. The effect consists of 2 components – high level of retention for the first few items which is called the primacy effect and high level of recall for the last few words which is called the recency effect.
To study the primacy and recency effect on recall.
A list of 32 words, which are categorised into 3 groups. The first group consisting of the first 8 words, the second group consisting of the middle 16 words and the 3rd group consisting of the last 8 words. The first and the third group of words are used for studying the primacy effect and the recency effect respectively.
The subject is seated comfortably and the following instruction is are given- “I will show you a list of words through the window of this apparatus (showing the memory drum). You see these words carefully. Each word will be shown to you only once and only for 3 seconds. You will have to remember and recall as many words as you can from this list of words”.
Each word is presented for 3 seconds and only one trial is given. At the end of the presentation of the list, the subject is asked to recall the words.
The experimenter records the number of words correctly recalled by the subject from each of the three groups of words and the results are to be tabulated as shown in Table I. The group data is to be presented as shown in Table II.
Using appropriate statistical analysis, the experimenter discusses:
1. Whether there is any significant of difference between the percentage recall of the words belonging to the three groups.
2. Whether there is any significance of difference between the Mean recall scores of the subjects for the first group of words and middle group of words, last group of words and Middle group of words.
3. Whether there is any impact of primacy effect and recency effect on the recall.
4. Whether the results of the experiment reject the null hypotheses relating to the primacy effect and recency effect on the recall.
One of the important areas of memory research today is related to the ways and means of improving memory. Usually, the methods are related to increasing efficiency in encoding images, words, etc.
It was found that recall for words and pairs of words improved greatly when the two words were connected by an image. For instance, when we link terms like ring and horse by an image, we establish a meaningful connection between them, which then serves as a retrieval path. Imagery then connects pieces of information in memory and these connections facilitate retrieval. This is the main principle behind mnemonic (a memory-aiding system).
The method of Loci is one of the frequently used menemonic techniques. In this method, the sequence of items or objects are connected to memory putting it in a place or location. The first object is related to the first location, second to the second location and so on.
Suppose a list of words consists of items on a shopping list e.g., bread, eggs, milk, potatoes. You might imagine a slice of bread on the dining table, eggs in the refrigerator, milk on the stove, potatoes in the basket etc. Once you have memorised the items this way, you can easily recall them in the listed order by simply taking a mental walk in your dining room and kitchen.
Like the method of loci, another commonly used method is the key word method of mnemonics.
To study whether the recall of words is better if a mnemonic system is employed.
This experiment is carried out as a group experiment. Two lists of words A & B, are prepared and two groups of subjects are used in this experiment. Subjects belonging to group I, learn list A first and then learn list B, whereas group II subjects learn list B first and then list A. This experiment is conducted under two conditions.
The following instructions are given- to group I, for learning list A and to group II for learning list B. “You will see a list of words. Each word will be shown to you for 5 seconds. Learn them. You will have to recall them as many as you can at the end of one exposure of each of these words.” After the entire list is shown once, the subjects are requested to recall as many words as they can. The number of words correctly recalled by each subject is his/her score.
The following instructions are given- to group I, for learning list ‘B’ and for group II for learning list ‘A’. “You will see a list of words. Each word will be shown to you for 5 seconds. But this time I would like you to learn these words by following the procedure, which I will explain to you now. Whatever the word you see, first have the image of that word and somehow associate this with an image of the next word. For example, suppose the first word is ‘dog’ and the second word is ‘gate’.
Now what you have to do is, first have the image of ‘dog’ and next, have the image of the dog standing near the gate and continue to do the same for all the other words. Once the total list of 10 words is presented to you, you will be asked to recall as many words as you can from the list of words you have seen”. After the entire list has been shown once, the subjects are requested to recall the words. The number of words recalled correctly by each subject is his/her score.
The scores obtained by each subject on list ‘A’ and list ‘B’ are tabulated as shown below:
The following points are discussed after employing the appropriate statistical analysis of the data:
1. Is there any significant difference in the number of words recalled under condition I and under condition II irrespective of the lists A and B?
2 Is there a significant difference in the number of words remembered by group I and group II under conditions I & II?
3. Do the results indicate any advantage of using a mnemonic technique while learning the list of words?
After the subjects have recalled the words under Condition I, they should be asked to explain how they remembered that many words, they may also be further probed to know whether they have used any mnemonic technique while learning the words.
This precaution is necessary to make sure that the subjects did not make use of any specific mnemonic technique. If any subject/ subjects used the mnemonic techniques in condition I itself, then their scores should be interpreted separately and should not be included in the group data.
Experiments on Imagination and Thinking:
To study individual differences in the ability to learn a concept in a multiple choice situation.
The Yerkes Multiple Choice Apparatus:
This apparatus consists of a box like board with a screen in the middle; on one side of the screen called (the subject’s side); there are twelve lights and also twelve switches one under each. On the other side again (experimenter’s side) there are an equal number of lights and switches below them. Under this row of switches, there is a row of buzzers, one buzzer corresponding to each light and also a row of switches (or a regulator) for the buzzers.
When the experimenter switches on a few lights on his side the corresponding lights on the subject’s side will also glow. The subject, however, can put these off by pressing the respective switches on his side. When the experimenter sounds the buzzers, the subject can stop the buzzer sound by using the same switches. (The buzzers and the lights are connected to the same switches on the subject’s side, but to different switches on the experimenter’s side.)
Multiple Choice Situation:
The experimenter switches on a number of lights and also at the same time sounds the buzzer opposite to one of the lights. The subject is to locate and press that switch which would stop the buzzer also. The experimenter follows a fixed principle in switching on the buzzer in the successive trials, e.g., always the left extreme or right extreme or second from the right, etc.
The experimenter gives the following instructions- “As soon as I say ‘ready’ you will see some of the lights before you, glowing and at the same time you will also hear a buzzer sound. By pressing one of the switches on your side, you will be able to stop the buzzer noise. Try to locate this switch and stop the noise.” The experimenter gives one or two demonstration trials.
Now the experimenter switches on about 6 to 7 of the lights and also the buzzer of one of these according to the principle he has chosen. The experimenter makes a note of the number of wrong switches pressed by the subject before he presses the right switch. The experiment is repeated several times, with different combinations of lights being switched on.
However, the buzzer is always switched on according to a specific underlying principle. Stop the experiment when the subject on three consecutive trials, straight away presses the correct switch without making any error. Ask him whether he has understood the principle behind locating the buzzing noise. If so, ask him to state it.
Tabulate the subject’s results in the following manner:
Tabulate the subject’s results in the following manner:
1. Discuss the individual differences in the number of trials required.
2. How do the errors decrease? Suddenly or gradually?
Learning starts as acquisition of information of specific objects or situations. With experience, however, we acquire information and form a general image of a whole class of objects, e.g., the child learns about the cow, the dog and soon about ‘animals’ as a whole. Thus the concept formation is possible because of two processes- generalisation and abstraction.
To study the process of concept formation.
A set of 36 cards with a design resembling Chinese ideographs.
The 36 cards fall into six groups or classes having 6 cards each. Each set of 6 cards have on them figures based on some basic design. This basic design is concealed by additional lines, dots, etc. Each of these 6 cards also has the same name printed on the back (This name is actually the name given to the basic design of this class). Thus, there are six class names for 36 cards.
The experimenter gives the following instructions- “I will be presenting to you a set of cards one after the other. I will also call out particular words after each card. Attend to it carefully. After exposing all the cards once I will expose them again and again, but on the subsequent presentations the names will not be called out. However, after each card is presented, you will have to call out the name of that card. If however, you are not able to do so for any particular card I will call the class name again”.
The experimenter in the first round presents each card for about 3 seconds and also calls out the name. After this, each card is presented again. If the name is wrong then the correct name is given. The trials are repeated until the subject is able to name all the cards. At the end of this, the subject is asked to give an introspective report as to how he learnt to give the names and also draw the characteristics for each name.
In scoring, the experimenter puts a tally for the correct response in naming the card and ‘P’ for the responses which have been an outcome of prompting. In each trial for each category there will be six responses.
Concept formation can also be studied by the test of concept formation devised by Kasanin and Hanfmann This test consists of 22 wooden blocks of different colours and shapes. The blocks, however, have two different height levels and also two different base sizes. The problem requires the subjects to classify these blocks into four groups by combining the criteria of height and base size. The four groups will be tall and large, tall and small, short and large and Short and small.
The subject is instructed as follows- “Here are a number of blocks. See if you can classify them into four groups on some principle.”
The experimenter makes a note of the various erroneous types of classification made by the subject and also the time taken before the subject arrives at the final correct classification. Besides, the experimenter takes an introspective report from the subject.
2. Collect group data for the number of erroneous classifications and time taken. Discuss the individual variations.
Experiments on Social Processes:
22. Autocratic and Democratic Groups and Work Output:
One of the most important experiments in social psychology was carried out by Lewin and his pupils Lippit and White. This experiment was conducted mainly to compare the efficiency of groups under two different types of leadership, namely autocratic and democratic. Since then, a number of social psychologists have carried out similar experiments.
To compare the work output of groups under autocratic and democratic leadership.
A large number of simple tasks of more or less equal difficulty- examples of such tasks are solving problems, fitting the parts of familiar objects, deciphering codes, etc.
Two matched groups are selected. One of these will work under an autocratic leadership and the other under a democratic leadership.
Group under Autocratic Leader:
An individual unknown to the members of the group is nominated as the leader of the group (leader should be one who knows the purpose of the experiment.)
The experimenter instructs the entire group including its leader, as follows:
Instruction- “This group of which you are all members will now have to solve a number of tasks. This person here (pointing to the leader) will be the leader. He is well – informed about the tasks to be solved. All the others in the group should obey him and do what he says. None of you should question him and he will guide you. There are several groups working in this manner, and the group which does best will be selected for an inter-school contest”.
The group is allowed to perform the various jobs. An observer makes a careful note of the tasks attempted, the number of correct solutions and also the emotional reactions of the various subjects. As soon as the 30 minutes are up, an introspective report is collected from each member with reference to his reaction to the leader, the group, and his willingness to continue as a member of the group.
Group under Democratic Leader:
With this group the following procedure is adopted.
The experimenter directs the group to select a leader from among themselves and then they are instructed as follows:
There are several groups like yours working in different rooms on certain jobs. The group which performs better than all the other groups will be sent for an inter-school contest. I am glad you have selected this person (pointing to the elected leader) as your leader. He will help you whenever you need some guidance. It is better that all of you consult each other and discuss how each one’s tasks could be solved. Such consultation will be very valuable.
The group is then presented with the various tasks again for 30 minutes. The rest of the procedure is similar to the procedure followed with the autocratic group.
Tabulate results as follows:
1. Compare the number of tasks attempted and correct solutions for the two groups and test the significance of the difference.
2. Compare the reactions of individual subjects to the group as a whole and to the leader in particular as revealed by the introspective reports of the subjects, and observations of the experimenter.
No group can function as a unit without uniformity and discipline of its members. In order to maintain uniformity, the members conform to the standards or norms set by the group.
When a member does not conform to the standards the group, exerts certain pressure on that member. Conformity is defined as any behavioural or attitudinal change that occurs as the result of some real or imagined group pressure. In simple words group pressure implies various situations or factors which enforce uniformity of pinion and behaviour in a group.
Innumerable studies have been conducted to study the factors affecting conformity. Experiments conducted by Sheriff prove that ambiguity of the stimulus is highly related to conformity. Asch, Luchins and Luchins, claim that increase in the size of the unanimous majority leads to greater conformity.
However, inspite of the pressure toward conformity, every group has its share of people who do not conform. Though some measure of conformity is necessary for co-ordinating group effort, a certain amount of non-conformity is essential for flexibility and adaptability of the group in changing conditions.
To demonstrate the phenomenon of conformity.
Two tachistoscopes marked A and B, two sets of cards totalling 120. They are divided into two sets A and B.
Set A consists of 60 cards with different designs:
20 cards – with a triangle drawn on each card
20 cards- with a circle drawn on each card
20 cards- with a vertical line drawn on each card
All the cards were shuffled and numbered 1 to 60.
Set B consists of 60 cards numbered from 1 to 60. Each card of this set corresponds to a particular card of Set A. with regard to the design and the card number i.e., it corresponds to its counterpart of Set A. Designs on all the cards in Set B are either smaller or equal or bigger compared to their counterparts of Set A. Out of the 60 cards, 45 cards have small dots on the top, towards the right hand corner.
Out of these,
15-cards-5 with each design having single dot.
15-cards-5 with each design having two dots.
15-cards-5 with each design having three dots.
The remaining cards have no dots.
Four students are selected for the experiment. Out of these, one is selected as a critical subject’, three as confederates’. The confederates are taken into the lab and are made to sit comfortably before the two tachistoscopes. The following instructions are given- one more person is going to join you for this experiment i.e., he is going to be the fourth person. He is going to sit there (pointing towards the empty chair placed at the extreme right).
After he comes I shall show you the cards one after the other through these windows. After exposing a pair of designs through these windows, I shall ask the fourth person (pointing to the empty chair) whether the design which is visible through Window B is smaller or equal or bigger when compared to the design which is visible through Window ‘A’ .
Listen carefully to what he has to say. I shall ask each one of you the same question. Look carefully towards the right hand corner of the card exposed through window ‘B’. If you do not find any dot, then three of you should express the same opinion or judgement expressed by the fourth person.
If you find a single dot, then, the person sitting next to him should pass the judgement which is contrary to the fourth person judgement. For example, if he says that the design of window B. is smaller than the one seen through window A, then one of you should say that it is equal or bigger compared to that of A; and others should agree with this judgement. If you see two dots, then two of you sitting next to him should disagree. If you see three dots, then all of you should disagree with his judgement.
Keep this in mind. You should neither consult each other nor speak about the dots during the experiment. After the fourth subject joins us, I shall give instructions to four of you I will not mention anything about the dots.
The fourth subject is asked to seat himself comfortably and the following general instructions are given- “These are the two windows (pointing A & B) through which I shall expose some designs one after the other. Tell me whether the design which you see through window B is smaller or equal or bigger than the design which you see through window A. Each one of you should express your opinion loudly so that I can make a note of it. Let us start from here (pointing to the fourth person). After you express your opinion we shall proceed to the next”.
The experimenter makes sure that subjects have followed his instructions. One experimenter exposes the designs, the other experimenter notes down each one’s opinion, starting from the critical subject covering all the confederates.
For a pair of cards, after all the subjects express their opinions, the experimenter asks each one to express his opinion again, starting from critical subject to confederates. Thus the experimenter repeats the procedure for all the cards until the cards of both the sets are exposed.
1. Cards of Set B are arranged according to the order in Set A.
2. The dots which are marked on the cards are light and barely perceptible.
Tabulate the results as follows:
Tabulate as shown below- the changes in the judgements of the critical subjects.
Discuss whether the critical subject emerged as a conformist or a non-conformist in the present experiment. If he is a conformist, then discuss the extent of conformity.