Leo Postman

SHORT-TERM TEMPORAL CHANGES IN FREE RECALL,

An experimental study of short-term memory for lists of familiar English words is reported. Lists of 10, 20, and 30 unrelated words were presented at a 1-sec. rate. Retention was measured by free recall after intervals of 0, 15 and 30 sec. A counting task was used to prevent rehearsal during the retention interval. The absolute level of recall increased with length of list whereas the percentages retained showed the reverse trend. The recall scores decreased steadily as a function of retention interval, with the rates of forgetting comparable for the three lengths of list. The decline in the amount recalled was due in large measure to the loss of the terminal items in the list. Consequently, the pronounced recency effect present on the immediate test of recall was progressively reduced as a function of time. By contrast retention of the initial part of the list was relatively stable. These variations in rate of forgetting are attributed to differences among serial positions in susceptibility to proactive inhibition.

Critical issues in interference theory

Critical issues in the theoretical and experimental analysis of interference processes in retention are reviewed. The evolution of classical two-factor theory is traced, and the strengths and weaknesses of the contemporary version of this p6sition are examined. Recent critiques of Current interference theories by Martin (1971a) and Greeno, James, and Da Polito (1971) are reviewed and examind. New conceptualizations of interference proposed by these authors, which place major emphasis on retrieval dependencies and on the role of encoding and retrieval processes, are considered and evaluated.

Temporal changes in interference

A series of five experiments investigating temporal changes in retroactive inhibition (RI) and proactive inhibition (PI) is reported. In the first four experiments changes in retention were measured by unpaced tests over intervals of the order of 20 min. Conditions of acquisition and methods of testing were varied with a view to identifying the factors determining absolute rises in first-list recall (“spontaneous recovery”) and decrements in the recall of interpolated lists (PI). Both of these phenomena were observed and were attributed to the dissipation of a set, established through interpolated learning, to give the most recently learned responses in recall. In the fifth experiment RI and PI were measured on paced tests after intervals of 20 min and 48 hrs. The amounts of RI and PI did not differ significantly after 20 min, and showed no further reliable changes over the 48-hr interval. The results indicate that the level of interference on paced tests is determined largely by the degree of reduction in response availability.

Short-Term Memory and Incidental Learning

Publisher Summary This chapter reviews experimental methods and findings in the study of short-term retention and incidental learning. There are important continuities between the theoretical and methodological problems in these two areas. Both types of studies are concerned with basic capacities and dispositions that the learner brings to the experimental situation and that determine the initial reception and immediate storage of information. Such experiments are not primarily designed to investigate the laws governing the integration of responses and the growth of associative strength. Rather, they are concerned with a detailed analysis of some of the conditions that limit and bias the subjects (Ss) responses in a learning situation. The extended practice takes its departure from these initial dispositions of the learner. In the conventional rote-learning experiment, exposures and tests follow each other in a fixed order within successive trials. When a single presentation of the learning materials is followed without delay by a test of performance, the measures of retention define the amount of immediate memory.

Transfer of training as a function of experimental paradigm and degree of first-list learning

Summary This study investigated transfer of training in paired-associate learning as a function of stimulus and response relationships and degree of first-list learning. Four paradigms of transfer were used, with familiar adjectives as both stimuli and responses: A-B, C-D (new stimuli and new responses); A-B, C-B (new stimuli and old responses); A-B, A-C (old stimuli and new responses); A-B, A-Br (old stimuli and old responses re-paired). Three degrees of first-list learning were used with each of the four paradigms: to a criterion of 6/10, to a criterion of 10/10, and to a criterion of 10/10 + 50% overlearning. All groups learned the same second lists whereas the composition of the first lists was varied in accordance with the requirements of the different paradigms of transfer. The second lists were learned to a criterion of 10/10 or for 10 trials, whichever took the longer. After the end of practice on the second list a modified test of free recall (MMFR) was administered in which S s were required to recall the responses from both lists. As evaluated against the control condition (A-B, C-D), all paradigms yielded negative transfer effects. The amount of negative transfer was greatest for A-B, A-Br, intermediate for A-B, A-C, and least for A-B, C-B. Performance on the second list improved as a function of degree of first-list learning but the amounts of transfer did not change reliably. There was some evidence, however, for progressive increases in negative transfer for A-Br relative to the other conditions. The results of the MMFR test show that amount of negative transfer and forgetting of first-list associations tend to be directly related. This relationship is attributed to the fact that competition from first-list associations leads to negative transfer as well as to the unlearning of these associations.

Encoding variability and retention.

The effects of encoding variability on retention were examined in three experiments. In Experiments 1 and 2, target words embedded in sentencees were presented three times, either in the same sentence or in different sentences. Encoding variability failed to increased either free or cued recall of the targets, nor did it reduce long term forgetting. In Experiment 3, phrases consisting of a class name and modifier were presented three times, with or without imagery instructions. The modifiers either remained the same or changed. Modifier variability had no overall effect on either immediate or delayed retrieval of the class names. Recall of modifiers was lower after variable than after constant encoding. It was concluded that an increase in the number of retrieval routes is not a sufficient condition of improved recall.

The Interpretation of Encoding Effects in Retention.

Recent experimental and theoretical analyses of the relationship between level of processing and retention are reviewed. In light of changing interpretations of encoding effects, the discussion centers on the status of depth of processing as an explanatory concept. Two studies are then reported in which predictions about the effects of orienting activities on retention were tested. In the first of these, the theoretically important interaction between level of processing and cue distinctiveness failed to materialize. In the second study, manipulations of the similarity between successive semantic orienting tasks failed to influence transfer and retroaction. The results point to important limitations on the control of encoding by orienting pasks.

The influence of orienting tasks on the encoding and recall of words

The effects of different orienting tasks on recall were investigated under both incidental and intentional conditions. In Experiment 1, type of processing (semantic or nonsemantic) was combined factorially with the dimension of rating (pleasantness or frequency of occurrence). Recall was higher (a) under the semantic than the nonsemantic conditions, and (b) after ratings of pleasantness than of frequency, regardless of the type of processing. It is suggested that displaced rehearsal is more probable when the rated attribute is purely subjective (pleasantness) than when it is objective (frequency). Thus, rating strategy influences recall. Experiment 2 shows that the difference between incidental and intentional learners increases as more stress is placed on the learning requirement in the instructions to the intentional subjects.

Studies of learning to learn: IV. Transfer from serial to paired-associate learning1

This experiment investigates the conditions determining transfer from serial to paired-associate learning. There were three conditions of transfer defined by the relationship between the successive lists. In Cond. E the paired-associate list consisted of all the pairs of adjacent items from the serial list; in Cond. C different items were used in the two lists, and in Cond. ER the paired associates were composed of nonadjacent members of the serial list. Under each condition of transfer there were an instructed group and an uninstructed group. After the end of serial learning the instructed group was informed about the relationship between the successive lists; the uninstructed group received no such information. All Ss served in three experimental cycles in each of which transfer from serial to paired-associated learning was measured. Significant amounts of positive and of negative transfer were obtained in Cond. E and Cond. ER, respectively. Instructions substantially enhanced positive transfer but failed to influence negative transfer. Positive transfer increased and negative transfer decreased as a function of practice. The results are consistent with the assumption that serial learning involves the development of sequential associations.

THE CALIFORNIA NORMS: ASSOCIATION AS A FUNCTION OF WORD FREQUENCY

Publisher Summary This chapter focuses on the California norms and presents norms of free association for samples of words varying widely in frequency of usage. Two sets of norms can be obtained, one by the method of discrete association and the other by the method of continued association or production. In a test of discrete association, S responds to a stimulus with the first single word that comes to mind. In a test of continued association, S gives as many responses to a stimulus as it can within a specified period of time. The mean number of different responses per unit of time defines a measure of meaningfulness of the stimulus word. The distribution of first responses to a stimulus generates an associative hierarchy comparable to that obtained from discrete associations. Word frequency is a major variable that is manipulated or must be controlled in most investigations using verbal materials. The total number of responses is fixed in discrete association; however, it is allowed to vary in continued association.