Verbal and spatial short-term memory: common sources of developmental change?

Verbal and spatial span, articulation and tapping rate, and verbal and spatial speed-of-search tasks were administered to sixty 6- to 12-year-olds. A variance-partitioning procedure was then used to identify age-related and age-invariant components of variance in span. Outcomes were very similar for verbal and spatial span, in particular, (i) most of the age-related variance was shared by the speed-of-search and rate predictors, (ii) articulation rate provided an age-independent contribution, (iii) changing-state versions of predictor tasks did not account for variance over steady-state versions, and (iv) predictors of the same modality as the span task did not outperform predictors of the other modality. We conclude that verbal and spatial short-term memory appear to rely on similar processes when serial recall is required and that developments in span are closely tied to increases in processing speed.     

Get the gist? The effects of processing depth on false recognition in short-term and long-term memory

Gist-based processing has been proposed to account for robust false memories in the converging-associates task. The deep-encoding processes known to enhance verbatim memory also strengthen gist memory and increase distortions of long-term memory (LTM). Recent research has demonstrated that compelling false memory illusions are relatively delay-invariant, also occurring under canonical short-term memory (STM) conditions. To investigate the contributions of gist to false memory at short and long delays, processing depth was manipulated as participants encoded lists of four semantically related words and were probed immediately, following a filled 3- to 4-s retention interval, or approximately 20 min later, in a surprise recognition test. In two experiments, the encoding manipulation dissociated STM and LTM on the frequency, but not the phenomenology, of false memory. Deep encoding at STM increases false recognition rates at LTM, but confidence ratings and remember/know judgments are similar across delays and do not differ as a function of processing depth. These results suggest that some shared and some unique processes underlie false memory illusions at short and long delays.     

Coding of spatial location information: an automatic process?

Several researches have claimed that spatial location information is automatically encoded, a claim supported by studies testing several criteria for the identification of automatic processes. However, a careful look at these studies reveals that some have not used appropriate testing methodology, the results of others have not complied with the criteria, and some criteria have not been examined at all. This article includes four experiments in which five criteria for testing the automaticity of cognitive processes were examined. Results show that memory for spatial location information is influenced by intention, age of subjects, competing task loads, practice, strategy manipulations, and individual differences. These results generally hold for memory of absolute location and for relative location information. The reported results are at odds with the claim that memory for spatial location information is exclusively mediated by automatic encoding processes. The concept of automaticity and the appropriateness of the testing criteria are discussed in light of the current results and recent findings on other features of the environment claimed to be automatically encoded.     

The effects of readers’ goals on inference generation and memory for texts

We investigated the effects of readers' goals on inference generation and memory for expository text. College students (N = 82) read texts for the purpose of either study or entertainment. On-line inference generation was recorded via think-aloud procedures, and off-line memory was assessed via free recall. Reading goal strongly influenced inferential activity: Readers with a study goal produced more coherence-building (i.e., backward/explanatory and forward/predictive) inferences, whereas readers with an entertainment goal produced more associations and evaluations. These differences were associated with superior memory for the texts in the study condition. The results indicate that inference generation during reading is partly strategic and is influenced systematically by reading purpose. We propose that reading goals influence readers' standards of coherence, which in turn influence the types of inferences that they draw and the final memory representations that they construct.     

The effects of distinctiveness on memory and metamemory for face–name associations

We examined the influence of face and name distinctiveness on memory and metamemory for face–name associations. Four types of monitoring judgements were solicited during encoding and retrieval of face–name pairs that contained distinct or typical faces (Experiment 1) or names (Experiment 2). The beneficial effects of distinctiveness on associative memory were symmetrical between faces and names, such that relative to their typical counterparts, distinct faces enhanced memory for names, and distinct names enhanced memory for faces. These effects were also apparent in metamemory. Estimates of prospective and retrospective memory performance were greater for face–name associations that contained a distinct face or name compared with a typical face or name, regardless of whether the distinct item was a cue or target. Moreover, the predictive validity of prospective monitoring improved with name distinctiveness, whereas the predictive validity of retrospective monitoring improved with facial distinctiveness. Our results indicate that distinctiveness affects not only the strength of the association between a face and a name, but also the ability to monitor that association.     

Which factors influence number updating in working memory? The effects of size distance and suppression

Updating information in working memory is a critical process which makes possible to have available, at every moment, the information most relevant for mind operations. However, the specific mechanisms underlying the updating process have rarely been analysed. This paper examines the importance of two of the mechanisms implicated in a numerical updating task: item comparison and item substitution. The item comparison mechanism was studied by manipulating the size distance between items. The item substitution mechanism was investigated by increasing/decreasing the number of updates within trials. Furthermore, in order to examine the effects of time constraints, presentation rate was manipulated. Over three experiments, the results obtained highlighted that updating performance is mainly influenced by suppression request, even when the presentation rate is self‐paced. However, errors depend on the distance between items. The implications of the results for the understanding of updating are discussed.     

The relationship between short-term memory and working memory: complex span made simple?

This experiment addresses the question of what makes a working memory measure a good predictor of higher-level abilities. Verbal and visuospatial processing episodes were interleaved with distinct verbal and visuospatial storage episodes to form four complex span tasks. Although these measures were reliable predictors of reading and mathematics ability in children, they were no more predictive of these abilities than corresponding simple span tasks involving storage alone. However, when individual differences in storage ability and processing capacity were controlled for, residual variance in complex span performance was related to academic ability in some cases. These findings indicate that complex span tasks are multiply determined, and that differences in task structure can dramatically influence the relative importance of these multiple constraints and the predictive power of a complex span measure.     

The effect of viewing distance on empirical discriminability and the confidence–accuracy relationship for eyewitness identification

The distance from which an eyewitness views a perpetrator is a critical factor for eyewitness identification, but has received little research attention. We presented three mock-crime videos to participants, varying distance to three perpetrators (3, 10, or 20 m). Across two experiments, increased distance reduced empirical discriminability in the form of a mirror effect, such that correct identifications decreased while false identifications increased. Moreover, high confidence identifications were associated with high accuracy at 3 m (Experiment 1 and 2) and 10 m (Experiment 2), but not at 20 m. We conclude that eyewitnesses may be less likely to identify a perpetrator viewed at a distance, and also more likely to falsely identify an innocent suspect. Furthermore, there may be certain boundary conditions associated with distance and the impact it has on the confidence–accuracy relationship. More research is needed to elucidate the effect of estimator variable manipulations on the confidence–accuracy relationship.     

How does horizontal and vertical navigation influence spatial memory of multifloored environments?

Although a number of studies have been devoted to 2-D navigation, relatively little is known about how the brain encodes and recalls navigation in complex multifloored environments. Previous studies have proposed that humans preferentially memorize buildings by a set of horizontal 2-D representations. Yet this might stem from the fact that environments were also explored by floors. Here, we have investigated the effect of spatial learning on memory of a virtual multifloored building. Two groups of 28 participants watched a computer movie that showed either a route along floors one at a time or travel between floors by simulated lifts, consisting in both cases of a 2-D trajectory in the vertical plane. To test recognition, the participants viewed a camera movement that either replicated a segment of the learning route (familiar segment) or did not (novel segment—i.e., shortcuts). Overall, floor recognition was not reliably superior to column recognition, but learning along a floor route produced a better spatial memory performance than did learning along a column route. Moreover, the participants processed familiar segments more accurately than novel ones, not only after floor learning, but crucially, also after column learning, suggesting a key role of the observation mode on the exploitation of spatial memory.     

The effect of an additional task on recall accuracy in serial short term memory: Preemption of rehearsal or acquisition?

In a serial short term memory test, being either visual or auditory, Ss got the additional instruction to make immediate binary classification responses (BcRs) to those items that occured after a marker which was presented somewhere in the list. The results show a general negative effect of BcRs on recall accuracy of both visually and auditory presented lists i.e. both on items which had been classified during presentation and on those which had occured before the marker arrived. The findings are contrary to the view that BcRs preclude acquisition of the items, but the hypothesis is confirmed that BcRs preempt intra trial rehearsal.     

The effects of laughter on discomfort thresholds: does expectation become reality?

Distraction and relaxation have been controlled in previous studies as possible mechanisms for the effectiveness of mirthful laughter in coping with pain and discomfort. The purpose of this study is to control expectation of benefit from laughter. Discomfort thresholds for a blood pressure cuff at the upper dominant arm were recorded immediately before and after exposure to either a humorous or a relaxation video. Instructional sets led participants to believe that the video would either increase or decrease their sensitivity to discomfort. A 5th group watched the humorous video without manipulation of expectation. All participants completed A. Ziv's (1979) Sense of Humor Questionnaire (SHQZ). Humor and relaxation videos raised discomfort thresholds, and the effect of both video types was enhanced by expectations. Humorous personality trait (SHQZ) did not moderate effects. The larger issue of whether mirthful laughter has any unique benefit for pain or discomfort control beyond the effects of relaxation, distraction, or expectation is discussed.     

Characteristics of spatial memory span: Is there an analogy to the word length effect, based on movement time?

In studies of verbal short-term memory it has been shown that the length of words to be remembered affects the size of memory span. This word-length effect is attributed to relationships between the rate of rehearsal of verbal material and the time it takes to speak the words being rehearsed. For spatial memory span there may also be an internal rehearsal system linked to overt responding, and if there is a strong analogy to be drawn between the verbal and spatial domains then movement time between spatial targets should predict the number of spatial locations that can be recalled. In the experiments reported here the time taken to move between spatial targets is varied by altering the size of targets and the distance between them. No difference between span performance on a nine-block spatial span task were found, either on immediate recall or on recall after an interval. When recall is of items from an array of 27, grouped in nine sets of three, with only one location in any set being presented on any trial, there is an effect of display size. This effect is consonant with the argument that movement time is related to spatial rehearsal, but other explanations are also possible. However, if recall in this task is scored over the nine sets rather than over the 27 items, then there is no difference between the displays. The results indicate that performance on the normal nine-block spatial-span task cannot be predicted by movement time.     

Cueing the location of a distractor: an inhibitory mechanism of spatial attention?

Presenting an irrelevant distractor increases reaction times to a target. The current study shows that cueing the location of an upcoming 'distractor' can help to reduce the effects the distractor has on target processing. It is hypothesized that this reduction is due to the active inhibition of the cued location. In two experiments in which the location of the distractor was cued in advance, a reduced effect of the distractor on target-processing was observed. Analyses indicated that this effect was most likely caused by inhibition of the distractor location. The present findings suggest that inhibition plays an important role in visual-spatial selection processes and that this inhibitory mechanism can be controlled in a top-down fashion.     

Experts’ memory: an ERP study of perceptual expertise effects on encoding and recognition

This study examined how perceptual expertise facilitates encoding and recognition. The electroencephalogram of car experts and car novices was recorded in the study as well as test phases of a remember/know task with car and bird stimuli. Car expertise influenced performance and event-related potentials (ERPs) for cars but not birds. Experts recognized and “recollected” cars more accurately, while novices had more false alarms. The ERPs provided neural evidence for theoretical assumptions about expert memory. Memory encoding in the study phase was less effortful and more elaborate for experts than novices, as indicated by lower mean amplitudes for subsequently “recollected” cars and by indistinguishable differences due to memory for recollection and familiarity. The parietal old/new effect, a correlate of recollection measured during recognition testing, was only found for experts. The results show that refined perceptual and semantic processing, characteristics of perceptual expertise, facilitate both memory encoding and recognition memory.     

The effect of word length in short-term memory: Is rehearsal necessary?

Three experiments investigated the effect of word length on a serial recognition task when rehearsal was prevented by a high presentation rate with no delay between study and test lists. Results showed that lists of short four-phoneme words were better recognized than lists of long six-phoneme words. Moreover, this effect was equivalent to that observed in conditions in which there was a delay between lists, thereby making rehearsal possible in the interval. These findings imply that rehearsal does not play a central role in the origin of the word length effect. An alternative explanation based on differences in the degree of retroactive interference generated by long and short words is proposed.     

The effect of word length in short-term memory: Is rehearsal necessary?

Three experiments investigated the effect of word length on a serial recognition task when rehearsal was prevented by a high presentation rate with no delay between study and test lists. Results showed that lists of short four-phoneme words were better recognized than lists of long six-phoneme words. Moreover, this effect was equivalent to that observed in conditions in which there was a delay between lists, thereby making rehearsal possible in the interval. These findings imply that rehearsal does not play a central role in the origin of the word length effect. An alternative explanation based on differences in the degree of retroactive interference generated by long and short words is proposed.     

Eye movements and serial memory for visual-spatial information: does time spent fixating contribute to recall?

This research investigated the nature of encoding and its contribution to serial recall for visual-spatial information. In order to do so, we examined the relationship between fixation duration and recall performance. Using the dot task--a series of seven dots spatially distributed on a monitor screen is presented sequentially for immediate recall--performance and eye-tracking data were recorded during the presentation of the to-be-remembered items. When participants were free to move their eyes at their will, both fixation durations and probability of correct recall decreased as a function of serial position. Furthermore, imposing constant durations of fixation across all serial positions had a beneficial impact (though relatively small) on item but not order recall. Great care was taken to isolate the effect of fixation duration from that of presentation duration. Although eye movement at encoding contributes to immediate memory, it is not decisive in shaping serial recall performance. Our results also provide further evidence that the distinction between item and order information, well-established in the verbal domain, extends to visual-spatial information.     

The effects of HIV disease and older age on laboratory-based,naturalistic, and self-perceived symptoms of prospective memory: does retrieval cue type and delay interval matter?

There is a rising prevalence of older HIV+ adults who are at risk of deficits in higher order neurocognitive functions and associated problems in everyday functioning. The current study applied multiprocess theory to examine the effects of HIV and aging on measures of laboratory-based, naturalistic, and self-perceived symptoms of prospective memory (PM). Participants included 125 Younger (48 with HIV, age = 32 ± 4.6 years) and 189 Older (112 with HIV, age = 56 ± 4.9 years) adults. Controlling for global neurocognitive functioning, mood, and other demographics, older age and HIV had independent effects on long-delay time-based PM in the laboratory, whereas on a naturalistic PM task older HIV? adults performed better than older HIV+ adults and younger persons. In line with the naturalistic findings, older age, but not HIV, was associated with a relative sparing of self-perceived PM failures in daily life across longer delay self-cued intervals. Findings suggest that, even in relatively younger aging cohorts, the effects of HIV and older age on PM can vary across PM delay intervals by the strategic demands of the retrieval cue type, are expressed differently in the laboratory and in daily life, and are independent of other higher order neurocognitive functions (e.g., retrospective memory).     

The effects of presentation rate and retention interval on memory for items and associations in younger adults: A simulation of older adults’ associative memory deficit

Older adults show an associative deficit in episodic memory compared to younger adults. Previous research suggests both strategic and automatic binding deficits contribute to older adults’ poorer memory performance. Using behavioral manipulations designed to affect strategic and automatic binding of associations, three experiments attempted to simulate an associative deficit in younger adults. In these experiments participants learned face-scene pairs and then were given item and associative recognition memory tests. We manipulated the time allotted at encoding and retrieval to simulate strategic deficits, and the length of the retention interval to simulate automatic deficits. Results indicate that both manipulations separately contribute to a differential decline in associative memory, similar to the one shown by older adults, especially as reflected in the differential increase in false alarm rate in the associative memory test more than in the item memory test. Considerations of possible underlying brain mechanisms are discussed.     

Episodic memory for object location versus episodic memory for object identity: do they rely on distinct encoding processes?

Three experiments were conducted to determine whether encoding processes that support episodic memory for object location are distinct from those that support memory for object identity. Guided by transfer-appropriate processing notions, we examined with an incidental learning paradigm whether an attentional focus on object location at encoding promotes subsequent recovery of object location, whereas a focus on object identity promotes recovery of object identity. We found that judging spatial relationships at encoding selectively supports recovery of object location, provided the test assesses memory for these relationships (rather than absolute location); our results also showed that judging physical and semantic object attributes promotes recovery of object identity preferentially. Contrasting with these domain-specific effects was evidence that identification processes involved in object naming boost memory for object identity as well as for absolute object location. Object identification at encoding may support memory performance in both domains by triggering the binding of identity and location information through a mechanism of object-based attentional selection.