The Influence of Long-term Memory Factors on Immediate Serial Recall: An Item and Order Analysis

In immediate serial recall, an error can occur because the presented item is not recalled (item error) or because it is recalled at the wrong serial position (order error). Even if these two types of information can be selectively influenced, in most current studies, a global performance measure confounding item and order information is used. Here, the issues associated with the measure of memory for item and order information are discussed. First, it is argued that in some circumstances it is very important that item information be controlled for when measuring order retention, by for example, conditionalizing order memory on memory for item information. Second, using such measures, it is shown that long-term memory factors recently investigated in immediate serial recall produce a different pattern of results than what is predicted by most current models: Semantic similarity, word frequency, and lexicality all influence item recall, but only lexicality affects order information. These findings are discussed in the light of a retrieval-based account suggesting that degraded phonological traces must undergo a reconstruction process calling upon long-term knowledge of the to-be-remembered items.     

Is there really very rapid forgetting from primary memory? The role of expectancy and item importance in short-term recall

In two experiments, subjects recalled one of two letter segments following a digit-filled retention interval. In Experiment 1, recall expectancy was manipulated by using precues that correctly informed or misinformed subjects concerning which letter segment wou;d be tested for recall. In Experiment 2, item importance was varied by precuing one segment as important but requiring that the uncued segment be recalled first. Recall performance was very low under conditions of low expectancy and low segment importance, but the slopes of the retention-functions did not demonstrate more rapid forgetting than under standard -conditions. The previous observations of very rapid forgetting from primary memory may be a function of an elevated initial recall level in the earlier studies. Our retention functions were compared with predictions of the Estes perturbation model. The findings suggested that when secondary memory processes were reduced, forgetting order information from primary memory occurred at the same rate as that estimated on the basis of previous studies using the standard distractor task.     

Recognition and position information in working memory for visual textures

In three experiments, we examined connections between item-recognition memory and memory for item-position information. With sequences of compound gratings as study and probe items, subjects made either item-position judgments (Experiments 1 and 2), by identifying the serial position of the study item that matched the probe, or recognition judgments (Experiment 3), by judging whether the probe had or had not been presented in the study series. Integrating a summed-similarity account of recognition into a signal detection framework shows that the variance of summed similarities on lure trials (probe not present in the study series) exceeds the variance on target trials (probe present in the study series). This prediction is borne out by the empirical zROC functions, all of which had slopes that were greater than 1. Additionally, about 25% of correct recognitions were accompanied by incorrect item position identification. Misidentifications of item position arose from two sources--structural similarity and positional similarity-which combined in an approximately additive fashion.     

Memory for Constrained and Preselected Movement Location and Distance

These experiments assessed the interrelationship between location and distance cues in the coding of movements. In separate experiments subjects recalled either the terminal location or the distance of constrained (Experiment 1) or preselected (Experiment 2) movements following a 15-sec retention interval. Changes in direction amd amplitude of starting position were used to ascertain whether recall errors were related to these changes. The findings of both experiments indicated that location and distance were recalled with similar accuracy when the starting position was identical for the criterion and recall movement. However, analysis of constant errors when the recall starting position was varied in either direction clearly indicated neither terminal location nor distance are coded independently, and memory for movement is based on an interaction between these cues.     

Fill-in and infill errors in order memory

Many current models of memory are specified with enough detail to make predictions about patterns of errors in memory tasks. However, there are often not enough empirical data available to test these predictions. We report two experiments that examine the relative frequency of fill-in and infill errors. In immediate serial recall tasks, subjects sometimes incorrectly recall item N too soon, placing it in position N-1. The error of interest is which item is recalled after this initial mistake. A fill-in error is the tendency to recall item N-1 next, whereas an infill error is the tendency to recall item N+1 next. Both experiments reveal more fill-in than infill errors, not only overall but at each possible error location throughout the list. The overall ratio is approximately 2:1. We conclude that none of the currently existing models adequately accounts for fill-in and infill errors.     

The role of attention in remembering important item-location associations

When encountering an excess of information, people are able to selectively remember high-value information by strategically allocating attention during the encoding period, termed value-directed remembering. This has been demonstrated in both the episodic verbal and visuospatial memory domains. Importantly, the allocation of attention also plays a crucial role in the binding of identity and location information in visuospatial memory. We examined how taxing attentional resources to various degrees during encoding might affect visuospatial memory and selectivity. Participants studied items paired with point values indicating their value in a grid display and were asked to maximize their point score (a summation of the points associated with correctly remembered information). Participants viewed items under either a sequential or simultaneous presentation format and in either the presence or absence of a secondary tone discrimination task. While participants in the divided attention conditions recalled fewer item-location associations overall, participants in all encoding conditions prioritized high-value information in memory, providing further evidence that selectivity can be maintained even when attentional resources are taxed. However, differences between presentation formats emerged when conducting spatial resolution analyses examining errors. Errors in the simultaneous conditions were only influenced by item value when attention was full during encoding, while errors in the sequential conditions were not influenced by item value, regardless of available attentional resources. The results suggest participants can strategically allocate attention during encoding even under cognitively-demanding conditions and that gist-based visuospatial memory may only be influenced by information importance when adequate attentional resources are available.     

Neuroanatomical correlates of category-specific semantic disorders: A critical survey

Current models of verbal short‐term memory (STM) propose various mechanisms for serial order. These include a gradient of activation over items, associations between items, and associations between items and their positions relative to the start or end of a sequence. We compared models using a variant of Hebb's procedure in which immediate serial recall of a sequence improves if the sequence is presented more than once. However, instead of repeating a complete sequence, we repeated different aspects of serial order information common to training lists and a subsequent test list. In Experiment 1, training lists repeated all the item–item pairings in the test list, with or without the position–item pairings in the test list. Substantial learning relative to a control condition was observed only when training lists repeated item–item pairs with position–item pairs, and position was defined relative to the start rather than end of a sequence. Experiment 2 attempted to analyse the basis of this learning effect further by repeating fragments of the test list during training, where fragments consisted of either isolated position–item pairings or clusters of both position–item and item–item pairings. Repetition of sequence fragments led to only weak learning effects. However, where learning was observed it was for specific position–item pairings. We conclude that positional cues play an important role in the coding of serial order in memory but that the information required to learn a sequence goes beyond position–item associations. We suggest that whereas STM for a novel sequence is based on positional cues, learning a sequence involves the development of some additional representation of the sequence as a whole.     

Temporal-spatial memory: retrieval of spatial information does not reduce recency

Factors influencing the shape of serial position curves in non-verbal serial short-term memory were examined, using a task testing memory for the position of dots. Similar recency slopes were found when both position and order were recalled (Experiment 1A) and when order only was required (Experiment 1B). This observation was confirmed and tested further in conditions requiring the same encoding but different amounts of spatial information at retrieval (Experiment 2). However, Experiment 2 also revealed an effect of spatial information retrieval on the overall level of memory for recency items. Overall, the results indicate that spatial items produce bow-shaped serial positions curves in tasks requiring the maintenance of order information and that recency is affected by the demand on spatial information retrieval in terms of the overall level of performance but not in terms of the recency slope. These findings are contrary to what is found in the literature on serial verbal recall when both item and order information are required.     

Positional and temporal clustering in serial order memory

The well-known finding that responses in serial recall tend to be clustered around the position of the target item has bolstered positional-coding theories of serial order memory. In the present study, we show that this effect is confounded with another well-known finding—that responses in serial recall tend to also be clustered around the position of the prior recall (temporal clustering). The confound can be alleviated by conditioning each analysis on the positional accuracy of the previously recalled item. The revised analyses show that temporal clustering is much more prevalent in serial recall than is positional clustering. A simple associative chaining model with asymmetric neighboring, remote associations, and a primacy gradient can account for these effects. Using the same parameter values, the model produces reasonable serial position curves and captures the changes in item and order information across study-test trials. In contrast, a prominent positional coding model cannot account for the pattern of clustering uncovered by the new analyses.     

Is there evidence for automatic processing of spatial and color attributes present in pictures and words?

The current experiment studies evidence for automatic processing of color and spatial dimensions present in matched pictures and words. Subjects studied four lists of either line drawings or matched words that varied in color (red or green) and position (left or right side), under one of four encoding conditions. Subjects were instructed to encode (1) only the item, (2) the item and its color, 13) the item and its position, or (4) the item and both color and position. All subjects participated in an unexpected final recognition task in which item recognition and recall for both attributes, regardless of original encoding instructions, we:re examined. Color memory appeared to be effortful for both pictures and words, as it was at chance level unless subjects were specifically instructed to encode the information. Position was most poorly recalled when subjects attended only to item information, but memory for this dimension was well above chance in all encoding conditions. The position of the line drawings was better recalled than the position of the words. The implications of these results for Hasher and Zacks’ (1979) model of automatic processes is discussed.     

Modeling the effects of irrelevant speech on memory

The feature model (Nairne, 1990) is extended to account for the effects of irrelevant speech and concomitant interactions in immediate serial recall. In the feature model, both articulatory suppression and irrelevant speech are seen as adding noise to the memory representation, the difference being that articulatory suppression diverts more resources than does irrelevant speech. The addition of noise impairs recall because it reduces the probability of successful redintegration. When a competitor is incorrectly recalled, rather than the correct item, this competitor is recalled out of order, producing an increase in order errors. Six simulations are reported that show that the model accounts for (1) the impairment by both irrelevant speech and articulatory suppression, (2) the irrelevance of the phonological and semantic composition of the irrelevant speech, (3) greater disruption when the irrelevant speech tokens vary, (4) the abolition of the phonological similarity effect for visual, but not for auditory, items, (5) the abolition of the word length effect for both visual and auditory items, and (6) the abolition of the irrelevant speech effect under articulatory suppression for both visual and auditory items. The feature model is compared with the two other major views of irrelevant speech, the phonological store hypothesis and the changing state hypothesis.     

Fill‐in and infill errors in order memory

Many current models of memory are specified with enough detail to make predictions about patterns of errors in memory tasks. However, there are often not enough empirical data available to test these predictions. We report two experiments that examine the relative frequency of fill‐in and infill errors. In immediate serial recall tasks, subjects sometimes incorrectly recall item N too soon, placing it in position N?1. The error of interest is which item is recalled after this initial mistake. A fill‐in error is the tendency to recall item N?1 next, whereas an infill error is the tendency to recall item N+1 next. Both experiments reveal more fill‐in than infill errors, not only overall but at each possible error location throughout the list. The overall ratio is approximately 2:1. We conclude that none of the currently existing models adequately accounts for fill‐in and infill errors.     

Feature bindings endure without attention: Evidence from an explicit recall task

Are integrated objects the unit of capacity of visual working memory, or is continued attention needed to maintain bindings between independently stored features? In a delayed recall task, participants reported the color and shape of a probed item from a memory array. During the delay, attention was manipulated with an exogenous cue. Recall was elevated at validly cued positions, indicating that the cue affected item memory. On invalid trials, participants most frequently recalled either both features (perfect object memory) or neither of the two features (no object memory); the frequency with which only one feature was recalled was significantly lower than predicted by feature independence as determined in a single-feature recall task. These data do not support the view that features are remembered independently when attention is withdrawn. Instead, integrated objects are stored in visual working memory without need for continued attention.     

Auditory presentation leads to better analogical retrieval than written presentation

Research on analogical retrieval suggests that cues with object similarity to a prior episode in memory lead to better retrieval than do cues with relational similarity. We suggest that previous work may have underestimated the effectiveness of relational cues, because this work has presented cues and targets in written format. There is some evidence that spoken presentations lead to better memory than do written presentations. We tested this hypothesis using a continuous reminding paradigm in which people read and recalled proverbs that were presented either in spoken or written format. The spoken format led to better retrieval from relational cues, particularly at longer lags between cue and memory item.     

The benefits and costs of repeated memory tests for young and older adults

Repeated and prolonged searches of memory can lead to an increase in how much is recalled, but they can also lead to memory errors. These 3 experiments addressed the costs and benefits of repeated and prolonged memory tests for both young and older adults. Participants saw and imagined pictures of objects, some of which were physically or conceptually similar, and then took a series of repeated or prolonged recall tests. Both young and older adults recalled more on later tests than on earlier ones, though the increase was less marked for older adults. In addition, despite recalling less than did young adults, older adults made more similarity-based source misattributions (i.e., claiming an imagined item was seen if it was physically or conceptually similar to a seen item). Similar patterns of fewer benefits and more costs for older adults were seen on both free and forced recall tests and on timed and self-paced tests. Findings are interpreted in terms of age-related differences in binding processes.     

On the relative and absolute strength of a memory trace

Subjects studied either an 8- or 16-word list and later recalled the items while a voice key recorded each response latency. The trials were partitioned by recall total in order to examine the means and distributions of both latencies and interresponse times as a function of recall total. Each analysis was consistent with the view that an item’s absolute strength determineswhether it is recalled whereas an item’s relative strength determineswhen it is recalled. In addition, mean latency was effectively proportional to study list length yet independent of recall total. All of the analyses were consistent with the view that the set of study items is sampled according to a relative-strength rule until all items are found and that a sampled item is recovered into consciousness only when its absolute strength exceeds a fixed threshold.     

Spatial attention based on 2D location and relative depth order modulates visual working memory in a 3D environment

The attentional effect on visual working memory (VWM) has been a heated research topic in the past two decades. Studies show that VWM performance for an attended memory item can be improved by cueing its two-dimensional (2D) spatial location during retention. However, few studies have investigated the effect of attentional selection on VWM in a three-dimensional setting, and it remains unknown whether depth information can produce beneficial attentional effects on 2D visual representations similar to 2D spatial information. Here we conducted four experiments, displaying memory items at various stereoscopic depth planes, and examined the retro-cue effects of four types of cues – a cue would either indicate the 2D or depth location of a memory item, and either in the form of physical (directly pointing to a location) or symbolic (numerically mapping onto a location) cues. We found that retro-cue benefits were only observed for cues directly pointing to a 2D location, whereas a null effect was observed for cues directly pointing to a depth location. However, there was a retro-cue effect when cueing the relative depth order, though the effect was weaker than that for cueing the 2D location. The selective effect on VWM based on 2D spatial attention is different from depth-based attention, and the divergence suggests that an object representation is primarily bound with its 2D spatial location, weakly bound with its depth order but not with its metric depth location. This indicates that attentional selection based on memory for depth, particularly metric depth, is ineffective.     

Spatial Imagery Preserves Temporal Order

Line drawings were presented in either a spatial or a nonspatial format. Subjects recalled each of four sets of 24 items in serial order. Amount recalled in the correct serial order and sequencing errors were scored. In Experiment 1 items appeared either in consecutive locations of a matrix or in one central location. Subjects who saw the items in different locations made fewer sequencing errors than those who saw each item in a central location, but serial recall levels for these two conditions did not differ. When items appeared in nonconsecutive locations in Experiment 2, the advantage of the spatial presentation on sequencing errors disappeared. Experiment 3 included conditions in which both the consecutive and nonconsecutive spatial formats were paired with retrieval cues that either did or did not indicate the sequence of locations in which the items had appeared. Spatial imagery aided sequencing when, and only when, the order of locations in which the stimuli appeared could be reconstructed at retrieval.