Evidence for working memory storage operations in perceptual cortex

Isolating the short-term storage component of working memory (WM) from the myriad of associated executive processes has been an enduring challenge. Recent efforts have identified patterns of activity in visual regions that contain information about items being held in WM. However, it remains unclear (1) whether these representations withstand intervening sensory input and (2) how communication between multimodal association cortex and the unimodal perceptual regions supporting WM representations is involved in WM storage. We present evidence that the features of a face held in WM are stored within face-processing regions, that these representations persist across subsequent sensory input, and that information about the match between sensory input and a memory representation is relayed forward from perceptual to prefrontal regions. Participants were presented with a series of probe faces and indicated whether each probe matched a target face held in WM. We parametrically varied the feature similarity between the probe and target faces. Activity within face-processing regions scaled linearly with the degree of feature similarity between the probe face and the features of the target face, suggesting that the features of the target face were stored in these regions. Furthermore, directed connectivity measures revealed that the direction of information flow that was optimal for performance was from sensory regions that stored the features of the target face to dorsal prefrontal regions, supporting the notion that sensory input is compared to representations stored within perceptual regions and is subsequently relayed forward. Together, these findings indicate that WM storage operations are carried out within perceptual cortex.     

Representation of memory for order of mental operations in cognitive tasks

Recent research shows that people learning a cognitive task acquire a memory for the order of operations applied, independent of the data to which those operations were applied. We designed two experiments to show how this sequence memory is represented. Experiment 1 compared predictions based on 3 possible sequence representation methods: composition, dyad transition, and associative chain. Latency and error results from a simple sequential task supported the associative chain representation. The associative links between operations presumably enhance performance by priming subsequent operations but do not operate in an all-or-none fashion. Experiment 2 explored whether transfer items that matched the first 2 rules and first 3 elements of a training item could bias participants toward executing a composed production learned during training. Latency and undetected error results were consistent with an associative chain representation but not with additional predictions made by the composition representation. These two experiments support the representation of operation sequences in memory as an associative chain.     

Autobiographical elaboration reduces memory distortion: cognitive operations and the distinctiveness heuristic

Retrieval monitoring enhances episodic memory accuracy. For instance, false recognition is reduced when participants base their decisions on more distinctive recollections, a retrieval monitoring process called the distinctiveness heuristic. The experiments reported here tested the hypothesis that autobiographical elaboration during study (i.e., generating autobiographical memories in response to cue words) would lead to more distinctive recollections than other item-specific encoding tasks, enhancing retrieval monitoring accuracy at test. Consistent with this hypothesis, false recognition was less likely when participants had to search their memory for previous autobiographical elaborations, compared to previous semantic judgments. These false recognition effects were dissociated from true recognition effects across four experiments, implicating a recollection-based monitoring process that was independent from familiarity-based processes. Separately obtained subjective measures provided converging evidence for this conclusion. The cognitive operations engaged during autobiographical elaboration can lead to distinctive recollections, making them less prone to memory distortion than other types of deep or semantic encoding.     

Editing misleading information from memory: Evidence for the coexistence of original and postevent information

When misleading postevent information biases one’s memory for an event, what is the fate of the original, accurate information? One possibility is that the new information and the original information coexist in memory, but that the former is simply more accessible. A second hypothesis suggests that the new information replaces the old, and memory is irreversibly altered. Using various retrieval techniques, Loftus and her associates (Greene, Flynn, & Loftus, 1982; Loftus, 1979a, 1979b) have failed repeatedly in attempts to recover original memories after postevent biasing, a finding that supports the alteration hypothesis. In the present study, postevent biasing was demonstrated in two experiments. In each experiment, some subjects were given a warning that the postevent information had included a few inaccurate details. These subjects were able to edit out the inaccurate details and to recover the original facts when the warning came as much as 45 rain after they had read the misleading information, a result that argues for the coexistence of memories. Successful recovery of the original memories was apparently due to the clarity of the warning and to an improved technique for assessing the retrieval of original memories.     

The role of attention in binding visual features in working memory: Evidence from cognitive ageing

Two experiments were conducted to assess the costs of attentional load during a feature (colour–shape) binding task in younger and older adults. Experiment 1 showed that a demanding backwards counting task, which draws upon central executive/general attentional resources, reduced binding to a greater extent than individual feature memory, but the effect was no greater in older than in younger adults. Experiment 2 showed that presenting memory items sequentially rather than simultaneously, such that items are required to be maintained while new representations are created, selectively affects binding performance in both age groups. Although this experiment exhibited an age-related binding deficit overall, both age groups were affected by the attention manipulation to an equal extent. While a role for attentional processes in colour–shape binding was apparent across both experiments, manipulations of attention exerted equal effects in both age groups. We therefore conclude that age-related binding deficits neither emerge nor are exacerbated under conditions of high attentional load. Implications for theories of visual working memory and cognitive ageing are discussed.     

Goal-directed memory: the role of cognitive control in older adults' emotional memory

The present study revealed that older adults recruit cognitive control processes to strengthen positive and diminish negative information in memory. In Experiment 1, older adults engaged in more elaborative processing when retrieving positive memories than they did when retrieving negative memories. In Experiment 2, older adults who did well on tasks involving cognitive control were more likely than those doing poorly to favor positive pictures in memory. In Experiment 3, older adults who were distracted during memory encoding no longer favored positive over negative pictures in their later recall, revealing that older adults use cognitive resources to implement emotional goals during encoding. In contrast, younger adults showed no signs of using cognitive control to make their memories more positive, indicating that, for them, emotion regulation goals are not chronically activated.     

Solving anagrams: Category priming and the differential availability of category solutions

An experiment was performed to test the hypothesis that the effect of category name priming on anagram solving varies with the strength of the relationship between the solution word and the priming category. Subjects solved anagrams of taxonomic category instances under primed or unprimed conditions. In the primed condition, the name of the taxonomic category from which the solution word was chosen was provided on each trial. Priming was shown to facilitate anagram solution and the extent of this facilitation was directly related to the instance dominance of the solution word in the priming category. The results were discussed in terms of current models of semantic memory.     

Making judgments about ability: the role of implicit theories of ability in moderating inferences from temporal and social comparison information

Two studies examined the novel proposal that implicit theories of intelligence (C. S. Dweck & E. L. Leggett, 1988) moderate both the effects of performance trends on ability inferences and the perceived diagnosticity of temporal versus normative feedback. Results from 613 adolescents and 42 teachers confirmed that entity theorists perceived initial outcome as more diagnostic and inferred higher ability in another (Study 1) and in the self (Study 2) in a declining outcome condition; incremental theorists perceived last outcome as more diagnostic and inferred higher ability in an ascending condition. Experimental induction of beliefs about ability had similar effects. As predicted, self-appraisal was affected more by temporal feedback among incremental theorists and by normative feedback among entity theorists. Results help resolve prior mixed findings regarding order effects and responses to temporal and normative evaluation.     

The representation of objects and their attributes in memory: Evidence concerning memory for location

The general principle is advanced that different attributes of objects (e.g. shape and colour) are more readily associated when they are attributes of the same object than when they are attributes of different objects. Previous studies provide support for the principle, for they have shown that a shape is more readily associated with its own colour than, for example, with the colour of its background. In the present experiments, the principle was applied to the attributes of shape and location. In four experiments it was shown that a shape was more readily associated with its own location than with the location of another object. Differences in contiguity between the presentation of the shape and the location with which the shape was to be associated were controlled for, as were other factors. The results were interpreted as providing support for the general principle stated above. It was suggested that the general principle could be explained by supposing that memory is propositional in format.     

Increased cognitive problem reporting after information about chemotherapy-induced cognitive decline: The moderating role of stigma consciousness

Objective: Information about treatment side effects can increase their occurrence; breast cancer (BC) patients showed increased cognitive problem reporting (CPR) and decreased memory performance after information about cognitive side effects. The current study extends previous research on adverse information effects (AIE) by investigating (a) risk factors, (b) underlying mechanisms and (c) an intervention to reduce AIE.

Design: In an online experiment, 175 female BC patients were randomly assigned to one of three conditions. In the two experimental groups, patients were informed about the possible occurrence of cognitive problems after chemotherapy with (intervention group) or without (experimental group) reassuring information that ‘there are still patients who score well on memory tests’. In the control group, no reference to chemotherapy-related cognitive problems was made.

Main outcome measures: Main dependent measure was CPR. Four moderating and five mediating processes were examined.

Results: CPR increased with higher levels of stigma consciousness in the two experimental groups, but not in the no-information control group.

Conclusion: Merely informing patients about cognitive side effects may increase their occurrence, especially among individuals vulnerable to patient stereotypes. Adding reassuring information is not sufficient to reduce AIE.     

Children's judgments about their own self‐knowledge: The role of disclosure to other

Previous research has suggested that children of 5/6 years fail to understand that they are the authority on their own self‐knowledge. That is, when asked questions like, ‘Who knows best when you are feeling tired?’, they tend to cite their mother rather than themselves. Here we report a study that, rather than asking about generalities (‘Who knows best what you are thinking?’), presented 5‐, 7‐ 9‐ and 11‐year‐children with hypothetical vignettes about specific circumstances in which they were described as either disclosing or not disclosing a specified state to their mother. Children were subsequently asked to judge who would best know the state. Over all age groups children were significantly more likely to identify themselves as authorities on their own self‐knowledge when states had not been disclosed to mother than when they had. However, in the case of disclosed states, young children (though not older ones) asserted that, ‘mum knows best’. These findings are interpreted as suggesting not that young children entirely fail to understand first person authority, but instead that they make the relatively sophisticated assumption that mothers' interpretive competence is greater than their own.     

The role of unconscious memory errors in judgments of confidence for sentence recognition

The present experiment tested the hypothesis that unconscious reconstructive memory processing can lead to the breakdown of the relationship between memory confidence and memory accuracy. Participants heard deceptive schema-inference sentences and nondeceptive sentences and were tested with either simple or forced-choice recognition. The nondeceptive items showed a positive relation between confidence and accuracy in both simple and forced-choice recognition. However, the deceptive items showed a strong negative confidence/accuracy relationship in simple recognition and a low positive relationship in forced choice. The mean levels of confidence for erroneous responses for deceptive items were inappropriately high in simple recognition but lower in forced choice. These results suggest that unconscious reconstructive memory processes involved in memory for the deceptive schema-inference items led to inaccurate confidence judgments and that, when participants were made aware of the deceptive nature of the schema-inference items through the use of a forced-choice procedure, they adjusted their confidence accordingly.     

Children's and adults' integration of information about noise and interest levels in their judgments about learning

This study examined developmental changes in the understanding of distractibility. It focused on how information about both interest level and noise level are used to form judgments of how many items a hypothetical child would learn. A total of 112 subjects from grades K, 2, and 5 and college age used a rating scale to judge the amount of learning in situations generated by a factorial combining of three levels of interest and three levels of surrounding noise. Children at all ages, even kindergarteners, used both noise and interest information in making their judgments. Interest level influenced judgments much more than noise level at all ages, but this imbalance waned somewhat with increasing age. The rules for combining noise and interest were more complex at the older ages. The discussion focused on interpretations of the subjects' belief that interest level heavily influences attentiveness.     

Illusions of competence and overestimation of associative memory for identical items: Evidence from judgments of learning

The relation between subjects’ predicted and actual memory performance is a central issue in the domain of metacognition. In the present study, we examined the influence of item similarity and associative strength on judgments of learning (JOLs) in a cued recall task. We hypothesized that encoding fluency would cause a foresight bias, so that subjects would overestimate recall of identical pairs (scale-scale), as compared with strong associates (weight-scale) or unrelated pairs (mask-scale). In Experiment 1, JOLs for identical word pairs were higher than those for related and unrelated pairs, but later recall of identical pairs was lower than recall of related pairs. In Experiment 2, the effect of encoding fluency (inferred from self-paced study time) was examined, and a similar pattern of results was obtained, with subjects spending the least amount of time studying identical pairs. We conclude that overconfidence for identical pairs reflects an assessment of item similarity when JOLs are made, despite associative strength being a better predictor of later retrieval.     

Rehearsal in serial memory for visual-spatial information: Evidence from eye movements

It is well established that rote rehearsal plays a key role in serial memory for lists of verbal items. Although a great deal of research has informed us about the nature of verbal rehearsal, much less attention has been devoted to rehearsal in serial memory for visual-spatial information. By using the dot task—a visual-spatial analogue of the classical verbal serial recall task—with delayed recall, performance and eyetracking data were recorded in order to establish whether visual-spatial rehearsal could be evidenced by eye movement. The use of eye movement as a form of rehearsal is detectable (Experiment 1), and it seems to contribute to serial memory performance over and above rehearsal based on shifts of spatial attention (Experiments 1 and 2).     

Adult age differences in memory for distinctive information: Evidence from the bizarreness effect

Two experiments examined age-related differences in memory for bizarre and common pictures. In Experiment 1, a facilitative effect of bizarreness was obtained for young adults and one of the older groups, but not for the oldest group (over age 70). However, the bizarreness effect was found for even the oldest group when predominantly common lists were used in Experiment 2. It is concluded that older adults suffer from deficits in distinctive processing, but those deficits can be reduced by providing a more uniformly common context in which differences can be processed.     

The role of the decision system in sensory and memory experiments using confidence judgments

This paper uses an artificial “sensory task” (a dice game) to investigate whether it is possible to distinguish between two-state and multistate sensory processes by examining confidence ratings of a group of unpracticed Os. The results indicate that Os use a decision rule that is deterministic so that both operating characteristics and a posteriori probability functions reflect the number of states used by the decision system. Thus, it would seem to be possible to use confidence ratings of Os to evaluate theoretical issues.     

Preserved learning of novel information in amnesia: Evidence for multiple memory systems

Four of five patients with marked global amnesia, and others with new learning impairments, showed normal processing facilitation for novel stimuli (nonwords) and/or for familiar stimuli (words) on a word/nonword (lexical) decision task. The data are interpreted as a reflection of the learning capabilities of in-line neural processing stages with multiple, distinct, informational codes. These in-line learning processes are separate from the recognition/recall memory impaired by amygdalohippocampal/dosomedial thalamic damage, but probably supplement such memory in some tasks in normal individuals. Preserved learning of novel information seems incompatible with explanations of spared learning in amnesia that are based on the episodic/semantic or memory/habit distinctions, but is consistent with the procedural/declarative hypothesis.