How to avoid aging effects in free recall

This brief review was prompted by an article appearing in an earlier issue of this journal (Cohen & Stewart, 1982). It identifies several conditions under which aging effects in free recall of complex materials may be avoided. Under these conditions the diminution of aging effects may occur even when strategic requirements are evident. Results are interpreted in terms of the contextual approach to life-span cognitive developmental psychology.     

A developmental study of attribute encoding in free recall

In two studies, subjects from second-grade, sixth-grade, and college were presented lists of unrelated words for single-trial free recall. Embedded in the list were critical items that were either semantically or phonemically related or else were completely unrelated. The sets of related items were either massed or distributed in the longer list. For second-graders, recall of Phonemic words was better than recall of Semantic words while the reverse was true for sixth-graders. Recall of Semantic distributed words by second-graders and of Phonemic distributed words by sixth-graders did not differ from recall of unrelated words. College students recalled Phonemic and Semantic words equally well and all related words better than unrelated words. Developmental trends were seen in the salience of particular attributes and in the utilization of low salient attributes.     

Interpreting semantic clustering effects in free recall

The order in which participants choose to recall words from a studied list of randomly selected words provides insights into how memories of the words are represented, organised, and retrieved. One pervasive finding is that when a pair of semantically related words (e.g., "cat" and "dog") is embedded in the studied list, the related words are often recalled successively. This tendency to successively recall semantically related words is termed semantic clustering (Bousfield, 1953; Bousfield & Sedgewick, 1944; Cofer, Bruce, & Reicher, 1966). Measuring semantic clustering effects requires making assumptions about which words participants consider to be similar in meaning. However, it is often difficult to gain insights into individual participants' internal semantic models, and for this reason researchers typically rely on standardised semantic similarity metrics. Here we use simulations to gain insights into the expected magnitudes of semantic clustering effects given systematic differences between participants' internal similarity models and the similarity metric used to quantify the degree of semantic clustering. Our results provide a number of useful insights into the interpretation of semantic clustering effects in free recall.     

A developmental study of relations between free recall, cued recall, and recall of incidental material

Six-, 9-, 17–19-, 45–55-, and 65-year-old subjects were shown 16 slides depicting one colored object and two uncolored context objects in a common setting, the task being to learn the names of the colored objects. Free and cued recall of both colored and context items were tested, the context objects being used as retrieval cues for the colored ones, and vice versa. The relative superiority of cued recall to free recall decreased regularly with increasing age. In the oldest subjects the level of free recall of TBR-objects was still fairly high, the level of recall of context objects being very low. The results support the hypothesis that adults encode nominally irrelevant context materials to a decreasing extent with increasing age, and that memory traces of young people in this sense are "richer", i.e., contain a greater number/variety of potential retrieval cues, than those of the elderly.     

Using overt rehearsals to explain word frequency effects in free recall

Three experiments examined the word frequency effect in free recall using the overt rehearsal methodology. Experiment 1 showed that lists of exclusively high-frequency (HF) words were better recalled, were rehearsed more, and were rehearsed to more recent serial positions than low-frequency (LF) words. A small HF advantage remained even when these 2 variables were equated. Experiment 2 showed that all these effects were much reduced with mixed lists containing both HF and LF words. Experiment 3 compared pure and mixed lists in a within-subject design and confirmed the findings of Experiments 1 and 2. It is argued that number of rehearsals, recency of rehearsals, and strength of interitem associations cause the word frequency effect in free recall.     

Association and categorisation effects on free recall

Lists of 18 words which varied in mean associative strength, the category membership of the associations and in word frequency were presented to subjects 3 times with recall required after each presentation. Recall efficiency increased with association level and with similarly categorised associates. In lists of High mean associative strength which consisted of similarly categorised words, the recall of high frequency word lists was facilitated but at low levels of associative strength, with similarly categorised words, recall was facilitated at both levels of word frequency used. Clustering and errors which were associatively related to the items being learned were greater in lists which contained sets of similarly categorised associates.     

Environmental context effects of background color in free recall

In four experiments, we investigated background-color context effects in free recall. A total of 194 undergraduates studied words presented one by one against a background color, and oral free recall was tested after a 30-sec filled retention interval. A signal for recall was presented against a background color throughout the test. Recalled items were classified as same- and different-context items according to whether the background colors at study and test were the same or different. Significant context effects were found in Experiments I and 2, in which two background colors were randomly alternated word by word. No context effects were found in Experiments 3 and 4, in which a common background color was presented for all items (Experiment 3) or for a number of successive items (Experiment 4). The results indicate that a change in background colors is necessary and sufficient to produce context effects. Implications of the present findings are discussed.     

How to avoid inconsistent idealizations

Idealized scientific representations result from employing claims that we take to be false. It is not surprising, then, that idealizations are a prime example of allegedly inconsistent scientific representations. I argue that the claim that an idealization requires inconsistent beliefs is often incorrect and that it turns out that a more mathematical perspective allows us to understand how the idealization can be interpreted consistently. The main example discussed is the claim that models of ocean waves typically involve the false assumption that the ocean is infinitely deep. While it is true that the variable associated with depth is often taken to infinity in the representation of ocean waves, I explain how this mathematical transformation of the original equations does not require the belief that the ocean being modeled is infinitely deep. More generally, as a mathematical representation is manipulated, some of its components are decoupled from their original physical interpretation.     

Hypermnesia in free recall and cued recall

In three experiments, categorized lists and both free recall and cued recall tests were used to examine hypermnesia. In Experiment 1, materials were drawn from obvious and nonobvious categories in an attempt to vary the amount of relational processing at encoding. The study materials in Experiment 2 consisted of a long word list that comprised several exemplars from each of a number of common categories. In Experiment 3, a single exemplar was drawn from each of 45 categories. In each experiment, similar magnitudes of hypermnesia were obtained on free and cued recall tests. Examination of the specific items recalled across tests indicated that similar processes underlie the hypermnesic effect for both test conditions. Implications of the results for extant accounts of the hypermnesic effect are discussed. It is concluded that the dynamics of retrieval processes change in a systematic fashion across repeated tests and the retention interval following study and that an adequate account of the nature of these changes in retrieval dynamics is essential to our understanding of hypermnesia and related phenomena.     

Spacing and lag effects in free recall of pure lists

Repeating list items leads to better recall when the repetitions are separated by several unique items than when they are presented successively; thespacing effect refers to improved recall for spaced versus successive repetition (lag > 0 vs. lag = 0); thelag effect refers to improved recall for long lags versus short lags. Previous demonstrations of the lag effect have utilized lists containing a mixture of items with varying degrees of spacing. Because differential rehearsal of items in mixed lists may exaggerate any effects of spacing, it is important to demonstrate these effects in pure lists. As in Toppino and Schneider (1999), we found an overall advantage for recall of spaced lists. We further report the first demonstration of a lag effect in pure lists, with significantly better recall for lists with widely spaced repetitions than for those with moderately spaced repetitions.     

Contextual variability and serial position effects in free recall.

In immediate free recall, words recalled successively tend to come from nearby serial positions. M. J. Kahana (1996) documented this effect and showed that this tendency, which the authors refer to as the lag recency effect, is well described by a variant of the search of associative memory (SAM) model (J. G. W. Raaijmakers & R. M. Shiffrin, 1980, 1981). In 2 experiments, participants performed immediate, delayed, and continuous distractor free recall under conditions designed to minimize rehearsal. The lag recency effect, previously observed in immediate free recall, was also observed in delayed and continuous distractor free recall. Although two-store memory models, such as SAM, readily account for the end-of-list recency effect in immediate free recall, and its attenuation in delayed free recall, these models fail to account for the long-term recency effect. By means of analytic simulations, the authors show that both the end of list recency effect and the lag recency effect, across all distractor conditions, can be explained by a single-store model in which context, retrieved with each recalled item, serves as a cue for subsequent recalls.     

Relationships between personality variables and bizarreness effects in free recall

Relationships between 6 personality variables and each of 3 different measures of recall for bizarre and common sentences were examined. The personality variables investigated included measures of sensation seeking, novelty experiencing, desire for novelty, arousal-seeking tendency, social potency, and conservatism. Recall was measured in terms of sentences accessed, target words recovered per accessed sentence, and misplaced target words. The results indicated the typical pattern of bizarreness effects on recall and significant relationships between personality variables and these effects. Arousal seeking and conservatism were positively related to a bizarreness advantage in sentences accessed. Additionally, high social potency was related to the recovery of more details from common than bizarre sentences, and high desire for novelty was related to a greater bizarre misplacement effect. The results are discussed in terms of orienting and defensive responses to bizarreness.     

Age dissociates recency and lag recency effects in free recall

The temporal relations among word-list items exert a powerful influence on episodic memory retrieval. Two experiments were conducted with younger and older adults in which the age-related recall deficit was examined by using a decomposition method to the serial position curve, partitioning performance into (a) the probability of first recall, illustrating the recency effect, and (b) the conditional response probability, illustrating the lag recency effect (M. W. Howard & M. J. Kahana, 1999). Although the older adults initiated recall in the same manner in both immediate and delayed free recall, temporal proximity of study items (contiguity) exerted a much weaker influence on recall transitions in older adults. This finding suggests that an associative deficit may be an important contributor to older adults' well-known impairment in free recall.     

The effects of classification structure on organized free recall in children

A sorting presentation procedure was used to study the effects of three classification schemes (self-generated, thematic, or taxonomic) on the organized free recall of second and fifth graders. Recall and clustering were significantly higher for subjects who used self-generated organizations than for subjects given the experimenter-prescribed taxonomic classification. The results indicated that memory performance benefitted when the organization of stimulus materials was consonant with children's personal classification structures.     

Detrimental influence of contextual change on spacing effects in free recall

Two experiments were conducted to determine the mechanism underlying the spacing effect in free-recall tasks. Participants were required to study a list containing once-presented words as well as massed and spaced repetitions. In both experiments, presentation background at repetition was manipulated. The results of Experiment 1 demonstrated that free recall was higher for massed items repeated in a different context than for massed items repeated in the same context, whereas free recall for spaced items was higher when repeated in the same context. Furthermore, a spacing effect was shown for words repeated in the same context, whereas an attenuated spacing effect was revealed for words repeated in a different context. These findings were replicated in Experiment 2 under a different presentation background manipulation. Both experiments seem to be most consistent with a model that combines the contextual variability and the study-phase retrieval mechanism to account for the spacing effect in free-recall tasks.     

Associative factors in free recall

An experiment on the free recall of 18-word lists is reported in which variations were made in associative frequency, word frequency and the number, and therefore size, of the presented groups. Recall efficiency was positively related to increasing associative frequency and larger presented group size. Measures of clustering were obtained along with subjects' own reports on the associative labels helpful to them in organizing their recall. A two-level storage model is proposed to account for the results.     

Organisational processes in free recall

In a free recall task, homogeneity of semantic reference and strong associative connections facilitated the recall after a twenty second filled interval of lists of 18 words. Facilitation in the recall of lists consisting of three sets of six related words when compared with six sets of three related words was also obtained. The organisation present in the recalled sequences is reported using various clustering measures and differences between the measures are indicated and discussed. Difficulties in the use of such measures in evaluating an hypothesis about the relationship between recall and organisation are illustrated and the general theoretical issue of selecting between alternative measures of organisation is considered.     

Recall termination in free recall

Although much is known about the dynamics of memory search in the free recall task, relatively little is known about the factors related to recall termination. Reanalyzing individual trial data from 14 prior studies (1,079 participants in 28,015 trials) and defining termination as occurring when a final response is followed by a long nonresponse interval, we observed that termination probability increased throughout the recall period and that retrieval was more likely to terminate following an error than following a correct response. Among errors, termination probability was higher following prior-list intrusions and repetitions than following extralist intrusions. To verify that this pattern of results can be seen in a single study, we report a new experiment in which 80 participants contributed recall data from a total of 9,122 trials. This experiment replicated the pattern observed in the aggregate analysis of the prior studies.     

The effects of learning instructions and cueing on free recall

Eighty unrelated high-imagery words were presented for free recall learning in groups of four words each. Learning instructions were varied, with one group told to relate the words in each input group by means of images, another group told to use verbal (sentence) mediators, and the control group not given specific learning instructions. During recall, list items were presented as retrieval cues in some conditions. In comparison with the control condition, imagery and verbal mediation instructions produced greater recall, more clustering, and a largez number of instances per group recalled. When the retrieval cues were selected such that one cue came from each of the input groups and when the strength of within-group organization was quite high, Ss recalled more words and a larger number of input groups. It was concluded that instructions and cueing conditions influenced different aspects of the free recall process. Instructions influenced the organization of individual words into units, and cueing affected the retrieval of specific units.     

The effects of visual presentation method on single-trial free recall

In two experiments four different conditions of visual presentation were studied with the purpose of furthering our understanding of the role of temporal and spatial factors underlying modality effects in single-trial free recall. Enriching spatial factors in the visual presentation did not produce a higher performance in the recency part of the serial-position curve, and it was therefore concluded that the modality effect could not be due to any visual handicap. A lag distribution measure was suggested and applied to the data to characterize output order (the order of recall) in single-trial free recall. The two experiments carried out used a within-subjects and a between-subjects design, respectively, and illustrate the importance of the methodological difference between these two designs.