Semantic processing and organization in free recall

It was hypothesized that both semantic processing and organizational activity are necessary for optimal free recall performance. In a series of three experiments, subjects were presented with a list of randomly selected nouns and were asked to make up a meaningful sentence for each noun. The subjects also rated the difficulty of using each noun. The subjects were instructed to try to remember words that were labeled "remember" words. For words that were labeled "story" words, the subjects were instructed only to make each sentence, using the word, part of an ongoing story which each subject was to make up. A test of retention for all presented words, using retention intervals of both 1 min and 24 h, showed that the story words were always recalled better than were the remember words. However, the amount of sequential organization was the same for both the story and the remember words. Recognition performance was found to be the same for both types of words. In addition, the story words were rated as being more difficult than the remember words. It was concluded that extensive semantic processing without organization is not sufficient for optimal recall.     

Executive processing in free recall of categorized lists

The present study examines the cognitive processes that operate in free recall of categorized lists by manipulating semantic structure of the lists and using a dual task methodology to restrict the processes that make demands on limited-capacity resources, the central executive resources. Relying on the assumption that, in free recall of categorized lists, the search for category names is a strategic controlled process that demands executive resources, lists with different numbers of categories ranging from 2 to 6 were employed. The results showed an effect of a secondary task on retrieval in the 4- and the 6-category list conditions, but not in the 2-category list condition. In contrast to retrieval, the secondary task interference at encoding produced an effect on recall of all three types of lists. An interesting finding was that an effect on clustering was found only when interference was present at encoding, not when it was at retrieval. This finding was in line with the suggestion (Troyer, Moscovitch, Winocur, Alexander, & Stuss, 1998) that switching (shifting between different category items) rather than clustering is related to executive functioning, and suggested that clustering may be a measure of two different types of processing: (1) executive processing at encoding and (2) automatic processing at retrieval. In addition, a different pattern of results was obtained when low frequency category words were used, indicating that the frequency of category words is an important determinant in free recall of categorized lists. Overall, the present results support the two-process account of retrieval of category words (Rosen & Engle, 1997) and the view that there are fundamental differences between encoding and retrieval processes (Naveh-Benjamin, Craik, Guez, & Dori, 1998; Naveh-Benjamin & Guez, 2000).     

Time of day and level of processing

The time of day at which material is presented has a differential effect on immediate and delayed retention. It has been suggested that this may be mediated by a shift in the type or level of processing that subjects spontaneously engage in. Three experiments are described that were designed to test this suggestion. Experiment 1 found the acoustic similarity effect on short-term memory to be greater at 1000 h than at 1900 h. Experiment 2 showed the semantic similarity effect on long-term memory to be greater at 1930 h than at 1030 h. Experiment 3 demonstrated that interposing a short-term memory task between the presentation of a list of words and its subsequent recall had a greater detrimental effect on list learning at 1030 h than at 1930 h. It is suggested that, if free to do so, subjects may spontaneously place more reliance on maintenance processing in the morning, but more on elaborative processing in the evening.     

Semantic processing can facilitate free recall in mildly retarded adolescents

The efficacy of semantic processing in free recall was investigated in two experiments with EMR adolescents. In Experiment 1, they were taught to use one of two semantic strategies for memorizing a 15-word list. Compared with controls, neither strategy helped recall either in original learning or transfer. In Experiment 2, one of the semantic strategies, a story mnemonic, was investigated further. Rather than being taught to construct their own stories as in Experiment 1, subjects in Experiment 2 were provided with experimenter-composed stories. They showed better immediate recall and retention after 2 months than did no-strategy controls. However, about 1 year after original learning, the retention of experimental and control subjects no longer differed. Discussion focused on the story mnemonic's potential utility and the criteria for judging such potential, e.g., amount of facilitation, ease of training and performance of the strategy, and the degree of its generalizability.     

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.     

Concreteness effects in free recall: The roles of imaginai and relational processing

Two experiments reevaluated the possible role of mental imagery in free recall of concrete and abstract words. In Experiment 1, the number and rate of list presentations were manipulated. Incidental recall following an imagery rating task yielded reliable concreteness effects after two presentations but not after a single presentation, regardless of presentation rate. In Experiment 2, we examined the effects of relational (categorization) and item-specific (imagery rating) processing tasks on memory for categorically related or unrelated concrete and abstract words. Concreteness effects were obtained when unrelated words were sorted into categories but not when they were rated on imagery. Related words failed to yield concreteness effects under any orienting condition. The results support the view that the presence or absence of concreteness effects in free recall depends on the relative salience of distinctive and relational information. This conclusion constrains theoretical explanations of the role of mental imagery in memory and cognition.     

Levels of processing with free and cued recall and unilateral temporal lobe epilepsy

This study investigates the role of the temporal lobes in levels-of-processing tasks (phonetic and semantic encoding) according to the nature of recall tasks (free and cued recall). These tasks were administered to 48 patients with unilateral temporal epilepsy (right "RTLE"=24; left "LTLE"=24) and a normal group (n=24). The results indicated that LTLE patients were impaired for semantic processing (free and cued recall) and for phonetic processing (free and cued recall), while for RTLE patients deficits appeared in free recall with semantic processing. It is suggested that the left temporal lobe is involved in all aspects of verbal memory, and that the right temporal lobe is specialized in semantic processing. Moreover, our data seem to indicate that RTLE patients present a retrieval processing impairment (semantic condition), whereas the LTLE group is characterized by encoding difficulties in the phonetic and semantic condition.     

Semantic and acoustic processing in free and cued recall by educable mentally retarded adolescents

The abilities of educable mentally retarded adolescents to encode and retrieve words with semantic and acoustic cues were investigated in a free and cued recall task. On each of three trial blocks, seven groups of subjects were presented 20 unrelated stimulus words. Groups received either semantic, acoustic, or no encoding cues along with the stimuli. Free recall was requested from all subjects, followed immediately by a second period of either free recall or cued recall with the semantic or acoustic cues. Semantic cues were most effective when presented both at encoding and retrieval. The subjects were unable to use acoustic information as effective retrieval aids. Results were discussed in terms of encoding dimension dominance and mediational deficiencies.     

Familiarity and free recall

Using stimulus material drawn from a single category, it is shown that formal recognition tests yield superior performance to recall when the category cannot be completely enumerated by the subjects, but not otherwise. Furthermore, within these categories recognition is superior only if unfamiliar items are selected as stimuli. These findings fit the theory that when recalling subjects attempt to scan the relevant category and “recognize” those items employed as stimuli.     

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.     

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.     

Understanding the dynamics of correct and error responses in free recall: Evidence from externalized free recall

The dynamics of correct and error responses in a variant of delayed free recall were examined in the present study. In the externalized free recall paradigm, participants were presented with lists of words and were instructed to subsequently recall not only the words that they could remember from the most recently presented list, but also any other words that came to mind during the recall period. Externalized free recall is useful for elucidating both sampling and postretrieval editing processes, thereby yielding more accurate estimates of the total number of error responses, which are typically sampled and subsequently edited during free recall. The results indicated that the participants generally sampled correct items early in the recall period and then transitioned to sampling more erroneous responses. Furthermore, the participants generally terminated their search after sampling too many errors. An examination of editing processes suggested that the participants were quite good at identifying errors, but this varied systematically on the basis of a number of factors. The results from the present study are framed in terms of generate-edit models of free recall.     

Reminiscence and item recovery in free recall

The item recovery or reminiscence component of recall in RTT procedures was investigated in two free recall experiments. In the first, Erdelyi and Becker's (1974) "hypermnesia" effect was found with pictures as the to-be-remembered material: total amount recalled increased over two successive test trials, and included a large reminiscence effect, with some 27% of previously unrecalled items appearing in the second test. The second experiment, with word lists, showed that the frequency of occurrence of new items was greater following a 12-min separation of two test trials than in two relatively massed tests. This kind of item recovery is relevant to models of output interference and retrieval limitations in free recall, and may be also related to spontaneous recovery effects.     

Developmental differences in rehearsal and free recall

The purpose of this experiment was to analyze developmental differences in rehearsal strategies which may mediate the commonly found age effect on free recall. As expected, significant age differences in recall were found; analysis of rehearsal strategies showed that fifth and eighth graders tended to repeat stimulus words immediately after presentation, and not enter items into subsequent rehearsal sets. Adults, in contrast, tended to reenter items for additional rehearsal, and had larger rehearsal buffers. Immediate repetition may have served as additional massed presentation trials, which are less consequential for learning than later reentry of items (spaced trials). It was inferred that children engaged primarily in maintenance rehearsal, and adults in both maintenance and elaborative rehearsal.     

Encoding variability and organization in free recall

Measures of category clustering and subjective organization are well-established predictors of performance in free recall tasks. The present studies demonstrate that a measure of encoding variability affords equally powerful and independent prediction of free recall performance. They also illustrate an interaction between encoding processes and organizational activity. In Experiments 1 and 2, the independent contributions of organization and encoding variability are demonstrated in categorizable and uncategorizable lists and in subjects whose recall is expected to increase (adults) or decrease (children) as a function of more varied encodings across trials. In Experiment 3, a category labeling procedure is used to demonstrate that the negative relationship between encoding variability and recall can be reversed by inducing adult-like organizational activity in children.