Sleep's function in the spontaneous recovery and consolidation of memories

Building on 2 previous studies (B. R. Ekstrand, 1967; B. R. Ekstrand, M. J. Sullivan, D. F. Parker, & J. N. West, 1971), the authors present 2 experiments that were aimed at characterizing the role of retroactive interference in sleep-associated declarative memory consolidation. Using an A-B, A-C paradigm with lists of word pairs in Experiment 1, the authors showed that sleep provides recovery from retroactive interference induced at encoding, whereas no such recovery was seen in several wake control conditions. Noninterfering word-pair lists were used in Experiment 2 (A-B, C-D). Sleeping after learning, in comparison with waking after learning, enhanced retention of both lists to a similar extent when encoding was less intense because of less list repetition and briefer word-pair presentations. With intense encoding, sleep-associated improvements were not seen for either list. In combination, the results indicate that the benefit of sleep for declarative memory consolidation is greater for weaker associations, regardless of whether weak associations result from retroactive interference or poor encoding.     

The role of horizontal categorization in retroactive and proactive interference

Four paired-associate experiments with a total N of 291 participants investigated the effects of horizontal categorization on retroactive and proactive interference. (Exclusively) horizontal categorization means that unique categorical relationships hold across the A-B and A-C stimulus-response pairs of successive word lists (e.g., fruit--pear, river--Thames, in list 1; and fruit--plum, river--Wolga, in list 2). Experiment 1 found no significant amounts of interference with this type of list organization. However, strong interference arose with the same materials when the categorical structure was destroyed in Experiment 2. A third experiment contrasted two alternative explanations for these results, and Experiment 4 replicated the effect of horizontal categorization (vs. no categorical relationship) in a within-participants design. The results of the four experiments largely fit with a response competition explanation proposed by Bower, Thompson-Schill, and Tulving (1994), adapted to the within-participants designs used here. Overall, the present findings add to a body of evidence demonstrating limits to retroactive and proactive interference.     

Strong memories obscure weak memories in associative recognition

The list strength effect, in which strengthening some memories has a detrimental effect on the retrieval of other memories, has generally not been found in item recognition. The present study shows that the list strength effect does occur in associative recognition. Study materials were sets of overlapping word pairs (A-B, A-C, D-B, etc.). Within critical sets of words, strong pairs were presented three times at study, as compared with one presentation for weak pairs. In Experiment 1, associative recognition for weak pairs was less accurate than that for baseline pairs, and response times for hits were slower. In Experiment 2, receiver-operating characteristic curve data provided further evidence of poor accuracy for weak pairs. These findings support a qualitative distinction between item and associative recognition.     

The effect of overlearning on transfer of training

The effect of overlearning on transfer of training on the A-B:A-B_r paradigm was studied in paired-associate learning with meaningful material (adjective pairs). One group of subjects was trained to criterion on list A-B, and two additional groups were given 100 per cent and 200 per cent overlearning on list A-B. Rate of learning list A-B_r was found to be directly related to amount of overlearning. Negative transfer on list A-B_r was found for errors with the criterion group, while positive transfer was found for the 100 per cent and 200 per cent overlearning groups. The results were consistent with previous paired-associate experiments, and with results of some maze, reversal learning experiments with infrahuman subjects.

The notation “A-B:A-B_r” will be used for the transfer paradigm in which the same stimuli and responses are used in both the original acquisition phase of paired associate learning and in the subsequent transfer of training phase. In the transfer phase, however, the responses (i.e. B) are rearranged so that they are paired with different stimuli (i.e. A). The notation “A-B:A-C” will be used for the transfer paradigm in which a new set of responses (i.e. C) are paired with the old set of stimuli in the transfer of training phase.     

Primacy effects induced by temporal or physical context shifts are attenuated by a preshift test trial

When subjects are sequentially trained with a cue (A) paired separately with two outcomes (B and C) in different phases (i.e., A-B pairings followed by A-C pairings) testing in the training context after short retention intervals often reveals recency effects (i.e., stronger influence by A-C). In contrast, testing after long retention intervals or testing in a context different from that of training sometimes reveals primacy effects (A-B). Three experiments were conducted using rats in a Pavlovian conditioned bar-press suppression preparation to ascertain whether a nonreinforced test trial in the training context soon after training can attenuate this shift to primacy. Experiment 1 demonstrated that exposure to A shortly after both phases of training, but prior to a long retention interval, can attenuate shifts from recency to primacy otherwise observed with a long retention interval. Experiment 2 showed that exposure to A in the training context can also eliminate the shift from recency to primacy otherwise produced by shifting the physical context between training and test. Experiment 3 discredited a potential account of the results of Experiments 1 and 2. The effects observed in Experiment 1 and 2 are interpreted as early testing in the training context serving to initiate rehearsal of the A-C association due to the temporal proximity of A-C training.     

Conditions favoring retroactive interference between antecedent events (cue competition) and between subsequent events (outcome competition)

Retrieval of a target association (A-B) is often impaired if training of a similar association is interpolated between target training and testing; this is known asretroactive interference. Two experiments, in which rats were used as subjects in a sensory preconditioning preparation, studied the associative nature of retroactive interference between antecedent events (i.e., A and C in the A-B, C-B paradigm) and between subsequent events (i.e., B and C in the A-B, A-C paradigm). With the present preparation, retroactive interference was equally strong between antecedent events and between subsequent events. Moreover, interference occurred only if (1) an association was trained in the interpolated phase and (2) the target and interpolated associations had a common element in a common temporal location.     

Reading skill and the minimum distance principle: A comparison of listening and reading comprehension

Experiment I compared the listening and reading comprehension of sentences which follow the Minimum Distance Principle, e.g., John tells Bill to bake the cake, and of those which do not, e.g., John promises Bill to bake the cake. Third, fourth, and fifth graders were tested. Support for Chomsky's Stage analysis of mastery of the Minimum Distance Principle was found for the listening but not for the reading task. Reading skill level was found to be positively correlated with Stage and a significantly better predictor of promise performance than was age or IQ. Experiment II investigated the effect of the composition of the experimental presentation list on performance by comparing comprehension when the list contained only promise or tell sentences with that obtained when the list contained both types of sentences. For half the subjects, performance differed as a function of the list composition: Implications of these findings for the assessment of the development of language competence are discussed.     

The effect of instructions to organize for good and poor learners

Two studies are reported which investigate the possibility that instructing individuals to organize their recall will differentially facilitate the performance of “fast” and “slow” learners (defined in terms of performance on a pretest). Experiment I utilized alphabetic organization in the free-recall learning of a list of unrelated words; Experiment II used a categorized word list under similar conditions. In each study, half of the individuals in each ability group received instructions, prior to the first of six learning trials, that contained information about the respective nature of organization present in the list and encouragement to use this type of organization in learning the list. In Experiment I, instructions to use alphabetic organization facilitated the performance of both ability groups to about the same extent. In Experiment II, instructions to use categorical organization in learning resulted in a substantial facilitation of performance for “slow” learners and a slight decrement in performance for “fast” learners. The results from the two studies are discussed in terms of sources of individual differences in learning.     

Control of adolescents' arbitrary matching-to-sample by positive and negative stimulus relations.

In Experiment 1, four developmentally delayed adolescents were taught an A-B matching-to-sample task with nonidentical stimuli: given Sample A1, select Comparison B1; given A2, select B2. During nonreinforced test trials, appropriate matching occurred when B stimuli appeared as samples and A stimuli as comparisons, i.e., the sample and comparison functions were symmetrical (B-A matching). During A-B or B-A matching test trials in which familiar samples and correct comparisons were presented along with novel comparisons, the subjects selected the correct comparisons. In tests with familiar samples and both incorrect and novel comparisons, subjects selected the novel comparisons, demonstrating control by both positive ("matching") and negative ("nonmatching") stimulus relations in A-B and B-A arrays. In Experiment 2, 12 developmentally delayed subjects were taught a two-stage arbitrary-matching task (e.g., A-B, C-B matching). Test sessions showed sample-comparison symmetry (e.g., B-A, B-C matching) and derived sample-comparison relations (e.g., A-C, C-A matching) for 11 subjects. These subjects also demonstrated control by positive and negative stimulus relations in the derived relations.     

Establishing Arbitrary Stimulus Classes via Identity-matching Training and Non-reinforced Matching with Complex Stimuli

The present study investigated whether training on an identity match-to-sample task followed by non-reinforced matching probes with complex stimuli leads to the emergence of multiple arbitrary matching performances and arbitrary stimulus classes in preschool children. In Experiment 1, eight subjects were trained on a colour-matching task (A-A). Then they received tests with complex AB and AC colour-form stimuli (AB-A, B-AB; AC-A, C-AC). These tasks were designed to help subjects respond to both elements of each complex stimulus. Subsequent B-A, C-A, A-B, A-C, B-C, and C-B tests revealed that all subjects had acquired class-consistent colour-form and form-form relations. Experiment 2 examined whether these results could be replicated when subjects were encouraged to respond to the colour elements of some (AB) complex stimuli and to the form elements of other (AC) stimuli. The procedures were the same as in Experiment 1 except that during the first test only A-AB and C-AC tasks were used. Six of eight subjects demonstrated all tested relations.     

Release from generation failure: The role of study list structure

Three experiments, using the original encoding-specificity paradigm, investigated the role of study list structure in producing Higham and Tam's (2005) generation failure effect. Generation failure occurs when cued recall performance for strong, extralist cues is worse than target production in a control group that is given no study list but is instead required merely to generate responses to the same test cues. In the present study, generation failure was replicated in Experiment 1, and Experiment 2 demonstrated that strong, extralist cues were more likely to elicit targets in pure generation groups when participants had studied a list of strong associates than when they had studied a list of weak ones. In Experiment 3, participants were released from generation failure when a study list of moderate associates was used and the cue-to-target associative strength was equated between the reinstated- and extralist-cue conditions. Together, these results suggest that generation failure is partly attributable to participants' searching inappropriate domains that, though consistent with the study list structure, are unlikely to contain targets.     

Review of Cultural Psychology,by Steven J. Heine

Summary

An A-B, B-C, A-C mediation paradigm was used to investigate observational learning of attitudes in a laboratory situation. The A-B stage involved the learning of dissyllables as responses to instances of three concepts. In the B-C stage, Ss observed a model apparently receiving different levels of shock in association with the dissyllables. In the A-C stage, Ss pulled a lever after the presentation of each of the previously learned concept instances and an equal number of new instances of the same concepts. During a second presentation, Ss gave evaluative ratings of the concept instances. The latency, speed, and amplitude of the lever pull response were not affected by the experimental manipulations. With respect to ratings, instances of concepts associated with shock to the model were significantly more disliked than instances of concepts not paired with shock to the model.     

Item-specific interference caused by cue-dependent forgetting

Memory for A-B word pairs (e.g.,child-apple) was tested by a cued recall test (e.g.,child-app__). Showing an A-C “relative” (e.g.,child-bicycle) reduced recall, especially if it was shown recently and was highly accessible (Experiments 1 and 2). In Experiment 3, a relative facilitated recall if it was semantically similar to the target (A-B′:child-cookies) but interfered if it was semantically dissimilar (A-C:child-fever). The best explanation for these results is that the relative primed features that affected the functional retrieval cue, and that interference occurred if the cue did not match the trace for the target (Martin, 1972). In other words, the interference effects are an example of cue-dependent forgetting. Neither blocking nor a discrimination process can account for these findings, although some evidence for a discrimination process has been found with other materials     

Symmetry training in pigeons can produce functional equivalences

Functional stimulus equivalence has been demonstrated using a transfer of training design with matching-to-sample training in which two sample stimuli are associated with the same comparison stimulus (A-B, C-B; many-to-one matching). Equivalence is shown by training a new association (A-D) and demonstrating the presence of an emergent relation (C-D). In the present experiment, we show that symmetry training, in which a bidirectional association is trained between two stimuli (A-B, B-A, using successive stimulus presentations followed by reinforcement), can also produce functional equivalence using a transfer of training design (i.e., train B-C, test A-C). The results suggest that training pigeons in the substitutability of two stimuli may be sufficient to produce functional stimulus equivalence between them. The results also have implications for the development of an emergent transitive relation, because training on A-B and B-C relations results in the emergence of an untrained A-C relation, if B-A training also is provided.     

Function transfer in human operant experiments: the role of stimulus pairings

Although function transfer often has been studied in complex operant procedures (such as matching to sample), whether operant reinforcement actually produces function transfer in such settings has not been established. The present experiments, with high school students as subjects, suggest that stimulus pairings can promote function transfer in conditions that closely approximate those of matching to sample. In Experiment 1, the subjects showed transfer of operant responding from three geometric figures (C1, C2, C3) to three colored shapes (B1, B2, B3) when the latter were paired with the former. Experiment 2 involved two groups of subjects. In the matching group, subjects matched the colored shapes with the geometric figures; in the yoked group, the shapes were merely paired with the geometric figures, and the schedule of stimulus pairing was yoked to the performance of the subjects in the matching group. Both groups of subjects showed function transfer. Experiment 3 documented function transfer from C stimuli to B stimuli through indirect stimulus pairings (A-B, A-C). In Experiment 4, function transfer was obtained even though the subjects vocalized continuously during the pairing trials, presumably preventing covert verbalization that might mediate transfer effects. Our results are consistent with a Pavlovian account and raise difficulties for current operant theories of function transfer.     

Comparative difficulty and the strategic regulation of accuracy: The impact of test-list context on monitoring and meta-metacognition

A growing body of research has shown that context manipulations can have little or no impact on accuracy performance, yet still significantly influence metacognitive performance. For example, participants in a test-list context paradigm study one list of words with a medium levels-of-processing task and a second word list with either a shallow or deep task: Recognition for medium words does not differ across conditions, however medium words are significantly more likely to be labeled as “remembered” (vs. merely familiar) if they had been studied with a shallow word list (Bodner & Lindsay, 2003). The goal of the current studies was to extend the test-list context paradigm to strategic regulation (report/withhold recognition test), and broaden it to incorporate different types of stimuli (i.e., face stimuli in place of a medium word list). The paradigm also was modified to include separate answer (studied/new) confidence and decision (report/withhold) confidence ratings at test. Results showed that context did not impact recognition accuracy for faces across the context conditions, however participants were more likely to report (i.e., volunteer) their face responses if they had studied the shallow word list. The results also demonstrated a difference between answer confidence and decision confidence, and the pattern of this difference depended on whether responses were reported or withheld (Experiment 1). Overall, the data are presented as support for the functional account of memory, which views memory states as inferential and attributional rather than static categories.     

Memory for internally generated words in Alzheimer-type dementia: breakdown in encoding and semantic memory

The "generation effect" is a phenomenon in which words that are generated by the subject are remembered better than words which are read. The present experiments examined this effect in patients with mild-to-moderate dementia of the Alzheimer type (DAT), healthy elderly adults, and young adults under a variety of different encoding and retrieval conditions. Experiment 1 employed an intentional learning task with multiple study/test trials using the same list of words. While both the young and elderly adults exhibited higher recall for internally generated words than read words, the DAT patients failed to demonstrate the effect even after repeated exposures to the same stimulus list. Experiment 2 replicated this same pattern of results using an incidental learning paradigm with both recall and recognition tests. Various explanations as to why the DAT patients failed to show the generation effect were discussed with particular emphasis placed on the role of semantic memory and encoding failure.     

Stimulus imagery and the effect of response categorization on recall in retroactive inhibition

This study deals with the interaction between characteristics of stimulus-response encoding and the effect of response categorization on recall in an A-B, A-C paradigm. After a discussion of the results of previous experiments by the present author a ‘restricted-constraint hypothesis’ is formulated. It states that category information will be used if the stimulus provides for an amount of constraint that is not sufficient for direct retrieval but still enough for identifying the response after the list as a whole has been retrieved. In the case of a high amount of constraint however, direct retrieval of the response is possible and category cues are bypassed. This hypothesis is tested by varying the Imagery-value of the noun-stimulus. A first experiment is inconclusive since the categorization effect fails to materialize. The second experiment comes out as predicted.     

The dual effect of context on memory of related and unrelated themes: Discrimination at encoding and cue at retrieval

The influence of contextual factors on encoding and retrieval in recognition memory was investigated using a retroactive interference paradigm. Participants were randomly assigned to four context conditions constructed by manipulating types of presentation modality (pictures vs words) for study, interference, and test stages, respectively (ABA, ABB, AAA, & AAB). In Experiment 1 we presented unrelated items in the study and interference stages, while in Experiment 2 each stage contained items from the same semantic category. The results demonstrate a dual role for context in memory processes-at encoding as well as at retrieval. In Experiment 1 there is a hierarchical order between the four context conditions, depending on both target-test and target-interference contextual similarity. Adding a categorical context in Experiment 2 helped to specify each list and therefore better distinguish between target and interferer information, and in some conditions compensated for their perceptual similarity.     

Memory for instances and categories in children and adults

College subjects and 7-year-olds were trained in sorting 16 words into two conceptual categories. Training consisted of either three list presentations (Experiment I) or training to solution (Experiment II). Then either immediately or after a 3 to 4 week delay subjects received a recognition test which assessed memory for the instance vs categorical properties of the task stimuli by embedding words from the original list and from the list categories with confusion items from either the same or different categories as those on the original list. The data indicated that learning and memory were controlled primarily by categorical properties of the task items in adults and by specific instance properties in children. However, there was evidence that children had learned the categorical attributes of the task and may have differed from adults chiefly in their failure to utilize these attributes to assist learning and memory performance. The age differences in learning and memory were independent of the degree of initial training.