Estimating item and order information

In a common psychological procedure, the subject is presented a sequence of items and is asked to recall them in order. His response is scored for items reported correctly in their correct position (position score) and for items reported correctly independently of position (item score). Such data are analyzed in terms of a model which assumes that a particular stimulus item may be forgotten entirely (State 0), may be remembered but without any knowledge of its position in the sequence, or may be remembered together with knowledge of its position (State 2). State 2 is related to the position score, and we define a nonexclusive State 1 (which contains all items not in State 0) that is related to the item score. In Part 1, we use the observed item and position scores to derive estimates of the trial-to-trial distribution of the number of items in States 1 and 2. In Part 2 we consider separately each serial position of the stimulus, and derive estimates of the probability that each individual item is in State 1 and State 2. The model handles omissions, second guesses, and gives sensitive estimates of partial information. Fast Fortran computer programs are available for all computations. In general, whenever responses are scored for items and/or for position, and when no alternative model is being tested, it is recommended that the above model be used to correct for the effects of guessing.     

Maintenance of item and order information in verbal working memory

Although verbal recall of item and order information is well-researched in short-term memory paradigms, there is relatively little research concerning item and order recall from working memory. The following study examined whether manipulating the opportunity for attentional refreshing and articulatory rehearsal in a complex span task differently affected the recall of item- and order-specific information of the memoranda. Five experiments varied the opportunity for articulatory rehearsal and attentional refreshing in a complex span task, but the type of recall was manipulated between experiments (item and order, order only, and item only recall). The results showed that impairing attentional refreshing and articulatory rehearsal similarly affected recall regardless of whether the scoring procedure (Experiments 1 and 4) or recall requirements (Experiments 2, 3, and 5) reflected item- or order-specific recall. This implies that both mechanisms sustain the maintenance of item and order information, and suggests that the common cumulative functioning of these two mechanisms to maintain items could be at the root of order maintenance.     

Perception and memory loss of item and order information in short-term memory

Recognition probes given before or after a series of letters presented at varying rates were used to evaluate perception and memory loss of order and item information. For both order and item information pre- and postprobe functions converged at fast rates of presentation. Performance decrement at fast rates is attributable to perceptual factors and is greater for order than for item information.     

The role of item distinctiveness in short-term recall of order information

In two experiments, we examined short-term recall of order information using a partial-report distractor task. We manipulated the characteristics of a single letter in one of two four-letter segments. Participants knew in advance the identity of the letters in each segment. We made a single letter distinctive at presentation either by printing it in red or by replacing it with a red dash. Presenting the letter in red did not affect overall recall of the positions of the letters in the segment but did facilitate specific recall of the position of the distinct letter. Replacing the letter with a red dash inhibited overall recall as well as specific recall of the distinct letter. Participants were also less likely to respond in the regular output order when there was a dash replacing a letter in the segment. These effects of distinctiveness are explained in terms of output order processes in recent versions of the perturbation model.     

Recall and recognition of order and item information in probed running memory, as a function of IQ

Two experiments were designed to test the possibility that correlations between IQ and probed serial running memory depend on IQ-related individual differences in the retention of order information in short-term memory. In Experiment I, correlations were obtained regardless of whether instructions emphasized serial recall or free recall. In Experiment II, a significant correlation between IQ and performance was obtained in a recognition test for very recent item information, but not in a recognition test for very recent order information. These data together with a theoretical analysis of the operations involved in the tasks, led to the conclusion that the correlations reflected individual differences in the capacity to access specified sets of items in very short-term memory.     

Dissociative effects of generation on item and order retention.

The effects of generation on the long-term retention of item and order information were examined in a between-list design in 3 experiments. In each experiment, completing word fragments during presentation significantly impaired long-term retention of serial order, as measured by either a reconstruction task or the amount of input-output correspondence in free recall. Memory for the individual items, however, was sometimes helped by generation. This pattern of dissociation, reminiscent of immediate memory findings, is used to interpret problematic issues in the generation effect literature and to argue for the role of the item-order distinction in the long-term-memory arena.     

Relations between vocabulary development and verbal short-term memory: The relative importance of short-term memory for serial order and item information

Although many studies have shown an association between verbal short-term memory (STM) and vocabulary development, the precise nature of this association is not yet clear. The current study reexamined this relation in 4- to 6-year-olds by designing verbal STM tasks that maximized memory for either item or serial order information. Although empirical data suggest that distinct STM processes determine item and serial order recall, these were generally confounded in previous developmental studies. We observed that item and order memory tasks were independently related to vocabulary development. Furthermore, vocabulary development was more strongly associated with STM for order information in 4- and 6-year-olds and with STM for item information in 5-year-olds. These data highlight the specificity of verbal STM for serial order and item information and suggest a causal association between order STM processes and vocabulary development, at least in 4- and 6-year-olds.     

Tests of encoding tradeoffs between item and associative information

The assumption that item and associative information are processed separately and that there is a tradeoff in the amount of each type of information that can be encoded in a given study interval (e.g., Anderson & Bower, 1972; Murdock, 1982, 1992) was examined. When item information was emphasized at study, recognition memory for associative information was poor, demonstrating that item information can be emphasized over associative information. In contrast, when associative information was emphasized, associative recognition greatly improved but item recognition did not suffer. This pattern of results was found at both fast and slow presentation rates, and for both high and low word concreteness and word frequency. Measures of confidence and response latency were also consistent with this pattern. Thus, the encoding of associative information did not measurably diminish item recognition performance.     

Question order bias in retrospective evaluations of item and associative recognition

Previous research has demonstrated a retrospective memory bias in metacognitive judgments regarding performance on general knowledge questions: Test-takers rate their own performance more optimistically when tests begin with easy questions than when tests begin with hard questions. An anchoring heuristic has been proposed to explain this finding, in which experience with the early questions constrains global performance evaluations of the test. In the current study we report on two experiments using tasks of item recognition and associative recognition to investigate the generality of question order bias. As predicted by an anchoring explanation, participants’ estimates of performance were higher for item recognition tests beginning with easy items. However, the effect was reversed in the associative recognition task: Participants’ estimates of performance were higher for tests beginning with hard items. Specific recollections, if present, may have a greater impact on test performance perception than more general global impressions.     

Retention characteristics of movement rate information

The retention characteristics of fast and slow movements were investigated in two experiments. Experiment 1 examined the reproduction of either fast or slow preselected movement rates after 0-sec rest, 15-sec rest or a 15-sec filled delay. Both fast and slow movement rates were rehearsable. Experiment 2 examined reproduction accuracy after subjects were required to perform a competing secondary task during the production of fast and slow movements. Although the secondary task degraded the reproduction of slow movements, it had no apparent effect upon the reproduction of fast movements. These results were interpreted as indicating partial support for Jones' (1974) notion of central monitoring of efference, and suggested that the contribution of proprioceptive feedback to movement control varies as a function of movement rate.     

Reading ability and the encoding of item and location information

Two experiments using duration exposures ranging from 20 to 130 msec are reported that link reading skill in adults to the initial encoding of location information. Highly skilled and less skilled readers were equivalent in identifying single letters presented at a central fixation point. When they had to identify the serial position of a letter, however, highly skilled readers performed significantly more accurately than did less skilled readers. A second experiment used displays that consisted of one letter and three dollar signs. Subjects had to identify the letter under two location cuing conditions. When subjects were cued in advance as to which serial position would contain the letter, highly skilled and less skilled readers were equivalent. When the location of the letter had to be resolved prior to identification, highly skilled readers performed significantly more accurately than did less skilled readers. Results are interpreted to suggest that the role of perception in reading has been underestimated because emphasis has been on item perception, and the perception of spatial location has been largely overlooked.     

Memory for item order and phonetic recoding in the beginning reader

A defect in immediate memory for item order is often attributed to poor beginning readers. We have supposed that this problem may be a manifestation of an underlying deficiency in the use of phonetic codes. Accordingly, we expected good and poor readers to differ in their ability to order stimuli that can be easily recoded as words and stored in phonetic form, but not in their ability to order nonlinguistic stimuli that do not lend themselves to phonetic recoding in short-term memory. The purpose of the present study was to test this hypothesis by examining the ability of good and poor readers to reconstruct the order of sets of briefly presented stimuli that varied in the extent to which they could be distinctively recoded into phonetic form: pictures of common objects versus nonrepresentational, “doodle” drawings. As expected, an interaction between reading ability and type of stimulus item was found, demonstrating the material-specific nature of poor readers' ordering difficulties. These findings support the hypothesis that a function of the phonetic representation is to aid in retention of order information, and that poor readers' ordering difficulties are related to their deficient use of phonetic codes.     

Sensory modality and method of item information presentation in memory

Investigated were differences in paired-associate learning for auditory versus visual modalities and within each modality the anticipation and study test methods of item presentation were compared. Extant reports re these two sensory modalities and of the two learning methods had been inconsistent. In this study of 40 university students, the learning of CVC-CVC nonsense syllable pairs was significantly better with the visual than with the auditory modality. The study-test method was significantly superior to the anticipation method in the visual mode. With auditory presentations, however, acquisition levels for both methods were the same. Significant interactions were observed between sensory modalities and methods of presentation. At present the retention interval theory (Izawa 1972–1979b) appears to account best for the varied findings with respect to the two methods of presentation.     

An item/order trade-off explanation of word length and generation effects

The item-order hypothesis suggests that under certain conditions increased item processing can lead to deficits in order processing, and that this produces a dissociation in performance between item and order tasks. The generation effect is one such example. The word length effect is seen as another instance where this trade-off might be observed. The following experiments compare word length and generation effects under serial recall and single item recognition conditions. Short words are better recalled than long words on the serial recall task but long words were better recognised than short words. The results are consistent with the item-order approach and support a novel explanation for the word length effect.     

Effects of language dominance on item and order memory in free recall,serial recall and order reconstruction

Spanish–English bilinguals (N = 144) performed free recall, serial recall and order reconstruction tasks in both English and Spanish. Long-term memory for both item and order information was worse in the less fluent language (L2) than in the more fluent language (L1). Item scores exhibited a stronger disadvantage for the L2 in serial recall than in free recall. Relative order scores were lower in the L2 for all three tasks, but adjusted scores for free and serial recall were equivalent across languages. Performance of English-speaking monolinguals (N = 72) was comparable to bilingual performance in the L1, except that monolinguals had higher adjusted order scores in free recall. Bilingual performance patterns in the L2 were consistent with the established effects of concurrent task performance on these memory tests, suggesting that the cognitive resources required for processing words in the L2 encroach on resources needed to commit item and order information to memory. These findings are also consistent with a model in which item memory is connected to the language system, order information is processed by separate mechanisms and attention can be allocated differentially to these two systems.     

Infant categorization: memory for category-level and specific item information

In an attempt to determine whether it is necessary to postulate abstraction processes in infant categorization, three experiments assessed retention of category-level information and information specific to category members. Using a visual recognition memory procedure, 10- and 13-month-old infants were familiarized with category instances containing both shared dimensional information and idiosyncratic features. The addition of idiosyncratic features to members of the familiarization category enhanced specific item memory for 13-month-old infants. However, this was not the case for the younger infants. The results of within-category test comparisons indicated that 10-month-old infants regarded information common to all members of the category as more familiar than information specific to individual exemplars. This occurred despite evidence that specific item information was retained in memory and available for retrieval during recognition tests. The findings are discussed in relation to exemplar and abstraction models of categorization.     

Maintenance of semantic information in capacity-limited item short-term memory

We report a semantic effect in immediate free recall, which is localized at recency and is preserved under articulatory suppression but is highly reduced when recall is delayed after an intervening distractor task. These results are explained by a neurocomputational model based on a limited-capacity short-term memory (STM) store, consisting ofactivated long-term memory representations. The model makes additional predictions about serial position functions in semantically cued recall, indicating capacity limitations caused by a displacement type mechanism, which are confirmed in a second experiment. This suggests that in addition to the phonological component in verbal STM, there is an activation/ item-limited component with semantically sensitive representations.