Working memory span development: A time-based resource-sharing model account.

The time-based resource-sharing model (P. Barrouillet, S. Bernardin, & V. Camos, 2004) assumes that during complex working memory span tasks, attention is frequently and surreptitiously switched from processing to reactivate decaying memory traces before their complete loss. Three experiments involving children from 5 to 14 years of age investigated the role of this reactivation process in developmental differences in working memory spans. Though preschoolers seem to adopt a serial control without any attempt to refresh stored items when engaged in processing, the reactivation process is efficient from age 7 onward and increases in efficiency until late adolescence, underpinning a sizable part of developmental differences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prefrontal cognitive processes: Working memory and inhibition in the antisaccade task.

Recent research suggests 2 principal processes are assessed in many neuropsychological tests of prefrontal functioning: the ability to keep transient information on-line (working memory) and the ability to inhibit prepotent, but incorrect, responses. The current studies examined the hypothesis that taxing working memory beyond some threshold can result in decreased inhibition, resembling the errors committed by patients with prefrontal dysfunctions. Across 3 studies, 70 nonpatient subjects were tested on the antisaccade (AS) task (D. Guitton et al, 1985)—a task sensitive to inhibitory deficits. Subjects were required to look in the opposite direction of a flashed cue, inhibiting the reflexive tendency to saccade to the cue. Subjects performed concurrent tasks that varied working-memory load. The results indicated that conditions with the highest working-memory load produced inhibitory errors comparable to patients with prefrontal dysfunctions. The findings are discussed in terms of the interaction between working memory and the inhibition of prepotent responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A model of hippocampal memory encoding and retrieval: GABAergic control of synaptic plasticity

The current view of the role of GABAergic interneurones in cortical-network function has shifted from one of merely dampening neuronal activity to that of an active role in information processing. In this review, we explore a potential role of hippocampal GABAergic interneurones in providing spatial and temporal conditions for modifications of synaptic weights during hippocampus-dependent memory processes. We argue that knowledge of spatiotemporal activity patterns in distinct classes of interneurone is essential to understanding the cellular mechanisms underlying learning and memory.     

Parallel memory retrieval in dual-task situations: II. Episodic memory.

Three experiments asked whether subjects could retrieve information from a 2nd stimulus while they retrieved information from a 1st stimulus. Ss performed recognition judgments on each of 2 words that followed each other by 0, 250, and 1,000 msec (Experiment 1) or 0 and 300 msec (Experiments 2 and 3). In each experiment, reaction time to both stimuli was faster when the 2 stimuli were both targets (on the study list) or both lures (not on the study list) than when 1 was a target and the other was a lure. Each experiment found priming from the 2nd stimulus to the lst when both stimuli were targets. Reaction time to the 1st stimulus was faster when the 2 targets came from the same memory structure at study (columns in Experiment l; pairs in Experiment 2; sentences in Experiment 3) than when they came from different structures. This priming is inconsistent with discrete serial retrieval and consistent with parallel retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parallel memory retrieval in dual-task situations: I. Semantic memory.

Can participants retrieve information about the 2nd of 2 stimuli while they are processing the 1st? Four experiments suggest they can. Reaction times to the 1st stimulus were faster if it came from the same category as the 2nd than if it came from a different category. This category-match effect was observed for letter-digit discrimination (Experiment 1), magnitude and parity judgments about digits (Experiment 2), and lexical decisions (Experiment 3). Experiment 4 showed that the 2nd stimulus could semantically prime the 1st. The category-match effect was observed only when the same task was performed on the 2 stimuli. When the task changed from the Ist stimulus to the 2nd, there was no advantage of a category match. This dependence on task set may explain previous failures to find parallel retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory, short-term memory, and general fluid intelligence: A latent-variable approach.

A study was conducted in which 133 participants performed 11 memory tasks (some thought to reflect working memory and some thought to reflect short-term memory), 2 tests of general fluid intelligence, and the Verbal and Quantitative Scholastic Aptitude Tests. Structural equation modeling suggested that short-term and working memories reflect separate but highly related constructs and that many of the tasks used in the literature as working memory tasks reflect a common construct. Working memory shows a strong connection to fluid intelligence, but short-term memory does not. A theory of working memory capacity and general fluid intelligence is proposed: The authors argue that working memory capacity and fluid intelligence reflect the ability to keep a representation active, particularly in the face of interference and distraction. The authors also discuss the relationship of this capability to controlled attention, and the functions of the prefrontal cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A diffusion model analysis of adult age differences in episodic and semantic long-term memory retrieval.

Two experiments investigated adult age differences in episodic and semantic long-term memory tasks, as a test of the hypothesis of specific age-related decline in context memory. Older adults were slower and exhibited lower episodic accuracy than younger adults. Fits of the diffusion model (R. Ratcliff, 1978) revealed age-related increases in nondecisional reaction time for both episodic and semantic retrieval. In Experiment 2, an age difference in boundary separation also indicated an age-related increase in conservative criterion setting. For episodic old-new recognition (Experiment 1) and source memory (Experiment 2), there was an age-related decrease in the quality of decision-driving information (drift rate). As predicted by the context-memory deficit hypothesis, there was no corresponding age-related decline in semantic drift rate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A neural system analysis of memory storage and retrieval.

Contends that from an information-processing viewpoint, memory can be subdivided into cue-access, short-term memory, and long-term memory storage and retrieval systems, which in turn are controlled by a number of operations, (e.g., match-mismatch, decay, and selective attention). Furthermore, it is assumed that specific neural substrates are maximally involved in the modulation of these specific processes essential to efficient mnemonic processing of information. Evidence is presented from previous studies to support this theoretical view of information processing. This evidence suggests that (a) the sensory systems and the cerebral cortex are critically involved in match-mismatch processing of information in the cue-access system, (b) the midbrain reticular formation and association cortex process information in the short-term memory system, and (c) the hippocampus is critically involved in consolidation and read-out of information in the long-term memory system. Evidence is also presented to suggest that after an initial preperceptual analysis information is transferred in parallel to the short-term and long-term memory systems, but that superimposed upon this parallel structure are sequential transfer processes (e.g., rehearsal). (6 p. ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task-set switching and long-term memory retrieval.

The authors tested the hypothesis of a close relationship between the intentional component of task-set switching ("advance reconfiguration;" R. D. Rogers & S. Monsell, 1995) and long-term memory (LTM) retrieval. Consistent with this hypothesis, switch costs are reported to be larger when the switched-to task involves high retrieval demands (i.e., retrieval of episodic information) than when it involves low retrieval demands (i.e., retrieval of semantic information). In contrast, switch costs were not affected by a primary-task difficulty manipulation unrelated to intentional retrieval demands (Experiment 2). Also, the retrieval-demand effect on switch costs was eliminated when time for advanced preparation or task cues explicitly specifying the task rules were provided (Experiment 3). Overall, results were consistent with the hypothesis that the intentional switch-cost component reflects the time demands of retrieving appropriate task rules from LTM. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of learning methods on collaboration: Prior repeated retrieval enhances retrieval organization, abolishes collaborative inhibition, and promotes post-collaborative memory.

Research on collaborative memory has unveiled the counterintuitive yet robust phenomenon that collaboration impairs group recall. A candidate explanation for this collaborative inhibition effect is the disruption of people's idiosyncratic retrieval strategies during collaboration, and it is hypothesized that employing methods that improve one's organization protects against retrieval disruption. Here it is investigated how one's learning method during the study phase—defined as either repeatedly studying or repeatedly retrieving information—influences retrieval organization and what effects this has on collaborative recall and post-collaborative individual recall. Results show that repeated retrieval consistently eliminated collaborative inhibition. This enabled participants to gain the most from re-exposure to materials recalled by their partners that they themselves did not recall and led to improvements in their individual memory following collaboration. This repeated retrieval advantage stemmed from the preferential manner in which this learning method strengthened retrieval organization. Findings are also discussed that reveal a relationship between retrieval organization and the interaction observed between learning method and short versus long delay seen in the testing effect literature. Finally, results show that the elusive benefits of cross-cuing during collaboration may be best detected with a longer study–test delay. Together, these findings illuminate when and how collaboration can enhance memory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Attention and retrieval from long-term memory.

Conducted 9 experiments with 152 female volunteers (mean age 44.4 yrs) to investigate the disrupting effect of a secondary task on retrieval from long-term memory. Exps I–V studied the influence of concurrent card sorting or digit span on free recall or paired-associate learning of word lists. Exp VI explored recall probability using a recognition paradigm in which accuracy and latency could be measured simultaneously. Exp VII explored the latency effect with a semantic memory paradigm, and Exp VIII required Ss to make semantic category judgments while retaining sequences of 6 digits. Exp IX examined the effect of concurrent digital load on the rate of generating items from semantic categories. Overall findings reveal that a demanding concurrent task did not reduce the probability of retrieving an item from semantic or episodic memory. However, concurrent load during learning substantially effected recall performance. A concurrent task during retrieval did not have a clear effect on latency. The contrast between the pattern shown by errors and by that shown by latencies suggests that attempts to estimate the attentional demands of any task should be interpreted with considerable caution when based on a single measure, such as performance errors, performance latency, or a response to a probe RT signal. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory and focal attention.

Measures of retrieval speed indicated that only a small subset of representations in working memory falls within the focus of attention. An n-back task, which required tracking an item 1, 2, or 3 back in a sequentially presented list, was used to examine the representation and retrieval of recent events and how control processes can be used to maintain an item in focal attention while concurrently processing new information. A speed–accuracy trade-off procedure was used to derive measures of the availability and the speed with which recent events can be accessed. Results converge with other time course studies in demonstrating that attention can be concurrently allocated only to a small number of memory representations, perhaps just 1 item. Measures of retrieval speed further demonstrate that order information is retrieved by a slow search process when an item is not maintained within focal attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory and changing-state hypothesis.

Effects of secondary tasks on serial short-term memory were investigated to test conflicting predictions derived from the working-memory model (A. D. Baddeley, 1986, 1997) and the changing-state hypothesis (D. M. Jones, P. Farrand, G. Stuart, & N. Morris, 1995). In Experiments 1 and 2, disruptions due to the changing-state characteristic of secondary tasks occurred in the encoding phase of spatial and verbal serial memory tasks but not in a retention interval. Experiments 3 and 4 revealed changing-state effects on tasks relying on central-executive resources. In Experiments 5 and 6, interference between central-executive demanding secondary tasks and serial short-term memory was larger during the encoding phase than the retention interval. Crossover dissociations emerged between spatial and verbal serial short-term memory. The results extend the findings of D. M. Jones et al. (1995) and support the working-memory account for interference in short-term memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory capacity and aphasia.

The talk presents a capacity theory of syntactic comprehension disorders in aphasia. The work described was done in collaboration with Patricia Carpenter and Akira Miyake. The theory assumes that aphasic patients still possess the structural (syntactic) and procedural knowledge necessary to perform syntactic analysis, but that they suffer from reductions in working memory capacity for language. The theory explains how reductions in working memory capacity can lead to the pattern of comprehension breakdown observed in aphasic patients. According to a resource-reduction view of comprehension impairments in aphasia, patients are assumed to have intact structural and procedural knowledge to parse various sentences, but suffer from consequences of severely reduced working memory resources. Two types of experiments provide relevant supporting data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional limits in memory retrieval.

The hypothesis that episodic memory retrieval can occur in parallel with other cognitive processes was tested in 2 experiments. Participants memorized words and then performed speeded cued recall (Experiment 1) or speeded yes-no recognition (Experiment 2) in a dual-task situation. The psychological refractory period design was used: The participant was presented with a single test item at various stimulus onset asynchronies (SOAs; 50-1,000 ms) after a tone was presented in an auditory-manual 2-alternative choice reaction task. Reducing the SOA increased the memory task reaction times. This slowing was additive with the effect of variables slowing retrieval in the memory task. The results indicate that memory retrieval is delayed by central processes in the choice task, arguing that the central bottleneck responsible for dual-task interference encompasses memory retrieval as well as response selection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory across nostrils.

Whether olfactory working memory involves verbal representations or neural images of odor per se remains unclear. This study investigated whether verbal representation influences performance in an olfactory delayed-match-to-sample task and used monorhinal presentation to generate hypotheses as to the underlying anatomy of this mechanism. The main findings were that (a) nameable odorants were easier to remember than hard-to-name odorants and (b) the nameability effect was more pronounced when the evaluation was done across nostrils. Considering these results within a proposed model implies dual representation in olfactory working memory: All odors, nameable and hard to name, are represented both perceptually and verbally. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A retrieval model for both recognition and recall.

Extended the search of associative memory model for recall proposed by J. G. Raaijmakers and R. M. Shiffrin (see record 1981-20491-001) by assuming that a familiarity process is used for recognition. The recall model posits cue-dependent probabilistic sampling and recovery from an associative network. The present recognition model is closely related to the recall model because the total episodic activation due to the context and item cues is used in recall as a basis for sampling and in recognition to make a decision. The model, formalized in a computer simulation program, correctly predicts a number of findings in the literature as well as the results from an experiment on the word-frequency effect in which 80 undergraduates participated. (3? p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and autobiographical memory: Dissociating episodic from semantic retrieval.

Cognitive aging research documents reduced access to contextually specific episodic details in older adults, whereas access to semantic or other nonepisodic information is preserved or facilitated. The present study extended this finding to autobiographical memory by using a new measure: the Autobiographical Interview. Younger and older adults recalled events from 5 life periods. Protocols were scored according to a reliable system for categorizing episodic and nonepisodic information. Whereas younger adults were biased toward episodic details reflecting happenings, locations, perceptions, and thoughts, older adults favored semantic details not connected to a particular time and place. This pattern persisted after additional structured probing for contextual details. The Autobiographical Interview is a useful instrument for quantifying episodic and semantic contributions to personal remote memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Storage and retrieval of associative clusters: A stages-of-learning analysis of associative memory traces.

In this research, the assumptions underlying the unitary trace theory of item representation and acquisition were tested in two cued-recall experiments in which the degree of preexperimental knowledge (typicality) was manipulated. Subjects learned lists of word triads (each of which consisted of a single cue and two targets) to a stringent acquisition criterion. In Experiment 1, typicality was manipulated in the absence of semantic relationships between members of the associative clusters. In Experiment 2, semantic relationships were present among cluster members, and preexperimental knowledge was manipulated by varying the degree of intracluster category membership as measured by whether cue and target items were typical or atypical category exemplars. In both experiments a mathematical model that embodies stages-of-learning distinctions was used to analyze the acquisition data. The results indicated that (1) cues and targets were represented in a single holistic memory trace, and (2) the manipulation of the degree of preexperimental knowledge affected both trace storage and retrieval learning, but had only a minimal impact on retrieval performance between the time a trace was stored and the time retrieval learning was complete. It was argued that these findings are consistent with a single unitary trace interpretation, namely, the modified storage-retrieval model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)