Most behavior involves sequences or chains of responses; reciting the alphabet is an obvious example. Starting a car and diapering a baby are other common sequences. When these sequences are studied experimentally in their simplest form, they are called serial-/earning tasks. We will discuss research in serial learning in this module. As you read the text, keep the following questions in mind.
Many behaviors have a sequence or order inherent in their execution. Such sequences occur whenever one response changes the situation so that a new response is called for. For example, turning the key in an ignition switch starts the car. Now a new set of responses are appropriate. We release the hand brake, put the car in gear, and so on.
Changes in the environment, or within the learner, which occur as a result of behavior are called response-produced stimuli. When these stimuli in turn elicit further action a sequence or chain results. Many complex activities may be analyzed as series of responses and response-produced stimuli, organized into chains. Figure 11 shows the beginning of a "car-starting chain." i Response Turn Key Feel Key Turn Hear Car Start Response-Prociuced Stimuli (Internal Stimulus) (External Stimulus) l I
Figure 11. "Car-starting chain" of activities
Not all response-produced stimuli come from the external environment. An important source of such stimuli is internal, such as muscular (kinesthetic) sensations associated with turning the ignition key. The kinesthetic feedback that comes from lifting a hammer tells us that it's high enough to strike the nail. External stimuli may also be present (for example, we can look to see if the hammer is raised). But in hammering, it is the kinesthetic, not the visual stimuli that are important. In the example of starting the car, auditory, visual, and kinesthetic stimuli all may arise from the "turn key" response. Even though we feel the key turn, we would not release the hand brake until the motor started and we could hear it run. Figure 12 shows further actions in the sequence. Response Stimulus Response Stimulus Hear Car Start~Release Hand Brake~Hand Brake Clicks~Put Car in Gear
Figure 12. Further actions in the sequence of car starting
A chain of behaviors is a series of responses to response produced cues
Response-produced cues can be observed in a wide variety of activities, from the simple memorization of a grocery list to complex problem solving tasks. In each case a response produces some change in the internal or external environment of the organism which acts as a stimulus or partial stimulus for the next act. There are many examples of chains in verbal learning. The child reciting the alphabet who has just said the letter F. reacts to his own vocalization as the stimulus for the next letter, G. In reciting a poem, each vocalization acts as a "cue stimulus" for the next vocalization.
Serial learning is considered a form of rote memorization in that it requires the subject to learn a list by repetition. Memorizing the lines of a play and learning a telephone number may both be examples of serial learning. In the laboratory situation, items (often nonsense syllables) are presented one at a time to the subjects. The sequence of the list is always the same. Initially, there is no way for the subject to know what item will be presented next. But, with repeated trials, he anticipates the syllables. For example, the subject might be given the following list to learn: DIV, COL, PIR, and so on. If the method of anticipation is used, the subject would be shown DIV and be expected to say "COL" before COL appears. When COL appears there is immediate confirmation of the response and should now respond "PIR."
The subject has reached mastery when all the syllables can be correctly anticipated. The subject may then be tested by being asked to recall the list in the correct order. Using this method, we can analyze the errors made to determine their possible cause. Such analysis indicates that not only are associations formed between adjacent pairs, but remote associations are formed to other items. If a subject in the above experiment erred in his response to the stimulus DIV, the most likely error would be to say "PIR." As might be expected, remote associations such as this would interfere with the correct association. In fact, as one continues into the list this interference is cumulative, so that later associations are harder to learn than earlier ones.
Figure 14. Errors in recalling a list of nonsense syllables
In learning long chains, various trials may be started at different points in the chain
Figure 14 shows a serial position curve. More errors are made on the item appearing in position 6 than that in position 2. On the other hand, since items near the end of the list have fewer associations coming after them, fewer interference effects are observed. The least amount of interference occurs at the two ends and the maximum amount of interference occurs in the middle of the list.
This is what McCrary and Hunter found (1953). Figure 14 shows the "hump" associated with serial position in the learning of nonsense syllables.
These data have implications for memorizing complex series. The technique of "taking it from the top that is, starting each practice trial from the beginning is usually not the most efficient way to learn a long serial task. Instead, one should give more practice to the middle portion.
The use of the maze has long been a favorite method of investigating serial learning in animals. The maze has the singular advantage that we can increase the complexity of the task by simply adding more choice points, as shown in Figure 15.
One of the early questions asked about such learning is: "What is actually being learned by the rat in the maze?" Watson proposed that the animal was responding to his own internal (kinesthetic) response-produced cues. He suggested that the muscular activity involved in making a left turn, for example, produced the cue for the next correct turn. Later experiments, however, have indicated the relative unimportance of internal stimuli as cues. McFarlen (1930) had rats first learn a water maze. The rats had to swim the entire length of the maze in order to reach a goal box. In later trials he put in a floor above the water. This did not alter the external appearance of the maze, but did force the animal to run rather than swim. The rats made no more errors when running than they had made when swimming.
In general, if an activity generates both internal and external response-produced stimuli, both forms may be effective. If the subject is denied one form he can respond to those that remain.
Now test yourself without looking back. (Questions 1-4 are omitted)
5. Here is a serial list
Which name would probably be the most difficult to learn?___________________________
6. Which of these actions depends on response-produced cues for its execution?
a. Eliciting a conditioned response
b. Emitting a paired-associate response
c. Learning a poem
7. Remote associations in serial learning are major sources of_________________________________________________
ANSWER KEY .
In serial learning, remote associations cause interference. The result is that the difficulty of learning an item in a list depends on its serial position. This graph shows difficulty as a function of serial position.
Remote association also acts to interfere with items in the last half of the list. Assume these items were in the last half of the list. Arrange them in their probable serial position from middle to end.
NOW TAKE PROGRESS CHECK 2
(These answers are for the nonsense syllables used in the graph not presented above. 1 BOD (middle) 2 (first) a, b VOP PIR REL XAN RET (end) DIB (middle) i
During a serial Learning experiment, the experimenter kept track of the mean errors made on each item. The results are as follows:
|XAN - 8.3||PIV - 9.1|
|TIV - 6.7||ZEV - 3.0|
|TOV - 4.5||NUZ - 1.9|
1. Which two items were probably the first and the last?_________________ and ____________________
2. Which two items were probably in the middle of the list? _________________ and ____________________
3. Which of these activities depend(s) on response produced cues for their execution?
a. Reciting lines of a play
b. Saying "four" when presented with a flash card with 2 + 2 on it
c. Running a maze
4. In a flow chart, the diamond stands for a___________________________event.
5. In maze learning, what stimuli may be effective?
a. Kinesthetic cues
b. Visual cues
6. The interference effect noted in serial learning comes from___________________________ associations.