Donald Robbins

The priority effect: Test effects on negative transfer and control lists

A study is reported investigating the “priority effect.” This effect refers to the finding of superior List 1 recall over List 2 on a MMFR test when the two lists conform to an A-B, A-D procedure. The result that the priority effect occurs only when no immediate test is given is confirmed. In addition, when AB-CD lists are used, no such effect is found. It is suggested that the assumption that the priority effect results from a process operating at the list level needs to be augmented based on these findings.

Memorial strategy and rated imagery value in recognition and free recall

Two studies were conducted in which rated imagery value and memorial strategy instructions were manipulated. Experiment I was a forced-choice recognition study and Experiment II was a free-recall task. The results revealed significant rated imagery effects in both studies. Neither task resulted in significant instruction effects. However, in the free-recall task, when Ss were presented with pairs of words, more pairs appeared to be recalled for interactive in contrast to separation imagery instructions, although this difference was not statistically reliable.

Repetition effects and retroactive facilitation: Immediate and delayed recall performance

A study was conducted using a continuous paired-associate task varying the retention interval after one of two presentations of a pair of words. The lag between presentations was also varied. Half of the two presentation items represented an A-B, A-C negative transfer design while the other half were A-B A-B items. Two different groups were instructed, with regard tc the A-B, A-C items, to recall on test trials only Response B or only Response C. Under some A-B, A-C conditions, retroactive-facilitation was found. Specifically, with a relatively long retention interval and short lags, the presentation of A-C was as effective as a second presentation of A-B for the recall of B.

Encoding variability theory and the spacing effect in associate learning

Encoding variability theory accounts for the spacing effect by assuming that, as the lag between repetitions increases, the memorial representations approach independence. A method for testing this assumption in determining repetition effects in associative learning is suggested. In the independence hypothesis, we simply assume that each presentation of a word pair is represented independently, so that the expected proportion recalled is simple, P=P1+P2 − PIP2. Two studies are reported using a continuous paired-associate task representing a factorial combination of lag and retention interval as well as single-presentation control conditions. The results indicate that for moderately long retention intervals, as the lag between repetitions increases, the observed proportion recalled is first less, then eventually exceeds, and then returns to the level expected by an independence hypothesis.

Individual organism probability matching with rats in a two-choice task

On any one trial, 10 rats had reward available for one of two alternatives, where the probability of reward for each alternative was 85:15, 70:30, or 30:70. The side on which reward was available was held constant until the rat responded to the rewarded side. First-choice trials, defined as trials following reward, revealed asymptotic probability matching in individual rats. Analysis of the error-run distributions revealed that Ss may have learned a conditional discrimination, i.e., trials following reward yielded probability matching behavior, while trials following nonreward at asymptote were largely to the side opposite the nonrewarded side.

Subproblem analysis of shift behavior in the gorilla: A transition from independent to cognitive behavior

Two gorillas (Gorilla gorilla) were trained on a series of two-dimensional problems, each problem involving an extradimentsional shift after original learning, then an intradimensional shift, followed by another extradimensional shift. The results indicated that during the early problems the subjects appeared to solve the problems as independent subproblems, i.e., using non-conceptual behavior. However during the last two or three problems the subjects appeared to shift to a conceptual mode of behavior. These data are interpreted as further evidence of the cognitive capacity of the gorilla.

Frequency judgments and the spacing effect: Immediate and delayed performance

A study was conducted using a continuous paired-associate task varying the retention interval after one or two presentations of a pair of words. The lag between presentations was also varied. Half of the items were tested immediately, and all of the items were tested after a delay. Subjects were instructed to recall the response and to indicate the presentation frequency for each item. The results indicated a lag effect only for items correctly judged as repetitions at the time of test on both immediate and delayed tests. Overall responding was generally greater for items given an immediate test in contrast to those only given the delayed test. The role of variable encodings and the representation of frequency in memory is discussed.

Pavlovian conditioning and signaling: Higher order conditioning and transfer in rats

Five rats were trained to barpress for food and then a first-order Pavlovian task (CS1-shock) was superimposed on this ongoing operant. Rapid suppression to CS1 was found. In the next phase, a second-order task (CS2-CS1) was superimposed on the ongoing operant, followed by CS1 extinction and then by CS2 probe trials. Evidence of second-order conditioning was found even after CS1 extinction, as has been previously reported. In the final phase, a third signal (CS3) was followed by CS1 and resulted in some suppression to CS3, although the response rate to CS1 during this phase was similar to that of the last day of CS1 extinction. The data suggest that when the CS1 was presented alone it resulted in behavior different from that when it followed a given signal.

Transfer after pattern discrimination in primates

Two squirrel monkeys and one infant orangutan were trained on a simultaneous discrimination between two stimuli that were identical except for a 90-deg difference in orientation. Subsequent transfer tests failed to reveal reliably the positive and negative anomalous transfer effects, i.e., preference for a solid-line stimulus over the original positive stimulus in the same orientation and preference for the original negative stimulus over a solid-line stimulus in the same orientation, respectively. Different transfer test procedures were implicated as being responsible for this failure, and it was suggested that additional exploration of the various transfer test procedures should be pursued before the generality of the anomalous effects could be established.

Cued recall performance of unrelated word pairs is reduced by the presence of A-B, A-C items in the same list

Repeated pairs of words can inhibit the recall of singly presented word pairs. This intralist inhibition is observed in cued recall tasks in which one list (homogeneous) contains only singly presented word pairs and another list (mixed) contains single and repeated word pairs. Recall of singly presented word pairs is worse when there are repeated word pairs than when there are not. In the present study, instead of repeating a pair, only the stimulus term was repeated, resulting in an A-B, A-C condition. Again, recall for singly presented pairs is worse in the mixed in contrast to the homogeneous list. That is, recall for the A-B pairs is worse for lists with both A-B and A-B, A-C pairs than for lists with only A-B pairs. The data are interpreted to indicate that presumably independent items sharing no common cues do nevertheless share a common retrieval route insofar as they have a common context, namely, being members of the same list.