James R. Whitman

Concept learning as a function of form of internal structure

Summary A concept-attainment experiment was run, using 16 stimuli formed from 4 dichotomous variables, and in which S s were required to learn a concept (subset of stimuli) of 8 of the 16. Two kinds of subsets of stimuli were used, one with a favorable form of internal structure involving a simple contingency between variables, and one with an interaction between variables. Three methods of presenting stimuli were used: the positive instances alone, both positive and negative instances with each kind grouped together, and both positive and negative instances intermixed. The results showed that the good form of internal structure strongly facilitated concept attainment except when the stimuli were intermixed. This result is interpreted to mean that the intermixing prevents perception of the characteristics of the subsets of stimuli. We have further argued that a primary function of presentation of negative instances in concept learning is to define the larger set of stimuli from which the particular subset is selected; and that if the subset itself defines the larger set, then negative instances can do no good and may make the problem more difficult.

Form and amount of internal structure as factors in free-recall learning of nonsense words

A series of free-recall learning experiments was carried out with visually presented nonsense words as stimuli, generated by using four letter words with two alternative letters per letter position. Five different groups of S s were presented with a total of 17 different learning problems involving variations in size of set of stimuli to be learned and in the internal structure of subsets of stimuli. The results are analyzed in the light of several problems in the psychology of learning: (1) Internal structure with simple contingencies between pairs of variables making up the stimuli provides relatively easy learning, while internal structure with no pair contingencies provides very difficult learning. (2) Learning difficulty is maximum as a function of length of list when the list is a subset of the total set, thus requiring learning of internal structure. The easiest-to-learn subsets of eight are as difficult to learn as the total set of 16 words. (3) Positive transfer or facilitation occurs if a subset is learned prior to learning of a total set, but not conversely; or when an easy subset of eight is learned prior to learning the complement of that set. (4) There is no difference between whole learning and part learning of either the total set or a subset as long as only easy-to-learn subsets are used as either parts or as wholes. Use of a difficult subset makes part learning of the total set ineffective.

Form of internal and external structure as factors in free-recall and ordered recall of nonsense and meaningful words

Groups of Ss learned four different lists of words by free-recall and then used the same words in an ordered recall learning task. The lists were so constructed as to represent the four combinations of two levels of association values and (a) two forms of internal structure for free-recall, and (b) two forms of external structure for ordered recall. The results indicated that forms of internal and external structure and not association values were critical when these were the forms hypothesized by Garner (1962) as favorable for each of the two learning tasks. Otherwise in both learning situations, the high meaningful material was learned in fewer trials.

Transfer effects in part to whole free-recall learning

Two experimental groups learned a list of four visual figures; one group learned these to the criterion of two perfect trials, and the second group received additional practice. A control group received no learning trials with the figures. All groups (N = 11 Ss each) then received practice on a list of eight figures, which included those learned by- the experimental groups. Positive learning transfer was shown only by the group receiving the overtraining. Transfer was not accounted for by an increase in the relative frequency with which overlearned stimuli were recalled while learning the eight stimuli.

IMPAIRMENT IN SERIAL LEARNING OF VISUALLY PRESENTED SPATIAL PATTERNS

Groups of schizophrenic, psychoneurotic, and brain-damaged patients and normal controls practiced reproducing a set of patterns briefly presented in a fixed order. The normal Ss learned these faster than the other groups, and the brain-damaged group had the greatest difficulty. There was no significant difference between the schizophrenic and the psychoneurotic groups. The results are interpreted as evidence of one type of learning impairment associated with these disorders.

Estrous activity in the white rat: A function of time spent in activity

The estrous activity cycle of the rat was analyzed to determine whether the variation in activity is accounted for by changes in rate of responding or duration of daily periods of activity. Running-wheel data indicated that time in activity is the critical variable.

Relationship Between Social Desirability Scale Value and Probability of Endorsement for Responses in Social Situations

Abstract Sixty-nine responses to the cartoons in the Rosenzweig P-F Study were shown separately to two groups. One group of 97 Ss rated each response on a 9-point scale of social desirability; a second group of 113 Ss indicated whether or not they themselves would make the response. The ratings on social desirability of the 69 responses were highly reliable. Secondly, there was a significant positive correlation between the social desirability scale value of a response and the per cent of Ss saying they would make that response. It is concluded that, as with items in personality tests, responses in social situations can be reliably evaluated in terms of social desirability and that such evaluations are associated with the probability of endorsement of these responses.

LEARNING IMPAIRMENT IN SCHIZOPHRENIC AND BRAIN-DAMAGED PATIENTS

An experiment reporting evidence of one type of learning impairment in schizophrenic and brain-damaged patients was replicated. Results supported the findings in the first experiment relating to these two diagnostic groups. A random sample of patients in the experiment was selected for additional testing. The correlations between performance in the experiment and intelligence test scores and also performance on a clinical test battery for diagnosing brain injury are reported.

The effect of nembutal on the estrous activity cycle

Abstract The purpose of this study was to determine whether or not the day of peak activity for rats showing regular estrous activity cycles is delayed by one day when sodium pentobarbital (Nembutal) is administered under the conditions found by Everett and Sawyer to be effective for delaying ovulation. Thirteen rats with regular 4-day estrous activity cycles received Nembutal and saline treatments on days of proestrus. Treatments were administered in a counterbalanced order; and after each, the day of peak activity in subsequent cycles was determined. For 12 of 13 animals treated with Nembutal the day of peak activity was delayed by one day; whereas for 11 of 12 animals, when saline was administered, the day of peak activity was not delayed.

Free Recall of Verbal Material in the Classroom as a Function of Method of Presentation and Method of Practice

Order in which stimuli were presented, and practice instructions were varied for 182 Ss receiving classroom practice on a free recall task with lists of nonsense words. The order within the list was a critical factor for the two levels of task difficulty used. Ss who studied the list gave more correct responses than did those who copied the list with the difficult material only. Ss then received additional practice with a second list. No facilitation in the free recall of the second list, attributable to the conditions which facilitated the learning of the first list, was found.