Slowing of memory-search performance in men with mild hypertension

Previous reports have associated hypertension with a slowing of cognitive performance, although the component processes involved have not been identified. Our report compares the performance of 24 men with mild hypertension and 28 age-matched normotensive men on a test of short-term memory search in which the duration of component processes could be estimated. The results indicated that the rate of search through short-term memory was slower for the hypertensive than for the normotensives, whereas the duration of encoding and response processes was equivalent for the two groups. This hypertension-related slowing of memory comparison was independent of participants' error rates and education levels.     

The role of working memory capacity in autobiographical retrieval: individual differences in strategic search

Remembering previous experiences from one's personal past is a principal component of psychological well-being, personality, sense of self, decision making, and planning for the future. In the current study the ability to search for autobiographical information in memory was examined by having college students recall their Facebook friends. Individual differences in working memory capacity manifested itself in the search of autobiographical memory by way of the total number of friends remembered, the number of clusters of friends, size of clusters, and the speed with which participants could output their friends' names. Although working memory capacity was related to the ability to search autobiographical memory, participants did not differ in the manner in which they approached the search and used contextual cues to help query their memories. These results corroborate recent theorising, which suggests that working memory is a necessary component of self-generating contextual cues to strategically search memory for autobiographical information.     

The role of working memory capacity in autobiographical retrieval: Individual differences in strategic search

Remembering previous experiences from one's personal past is a principal component of psychological well-being, personality, sense of self, decision making, and planning for the future. In the current study the ability to search for autobiographical information in memory was examined by having college students recall their Facebook friends. Individual differences in working memory capacity manifested itself in the search of autobiographical memory by way of the total number of friends remembered, the number of clusters of friends, size of clusters, and the speed with which participants could output their friends' names. Although working memory capacity was related to the ability to search autobiographical memory, participants did not differ in the manner in which they approached the search and used contextual cues to help query their memories. These results corroborate recent theorising, which suggests that working memory is a necessary component of self-generating contextual cues to strategically search memory for autobiographical information.     

Why search for target absence is so slow (and careful!): the more targets there are, the more likely you are to miss one

Five factors were tested as possible explanations of why it takes longer to find the critical row that does not contain a target letter (search for absence) than the critical row that does contain a target letter (search for presence). Various stratagems (e.g., asking subjects to search for a letter not in the memory set, presenting one row at a time and requiring a response to each row, and examination of sequential effects) led to the rejection of Factor 1 (Slower Processing of Targets), Factor 2 (Slower Recovery from Targets), Factor 3 (Spatial Chunking or Use of Peripheral Vision), and Factor 4 ( Temporal Chunking). The evidence favored Factor 5 (Opportunity for Misses): Targets, which as a rule are easy to miss, are relatively more numerous in search for absence, so to avoid making many more errors, the subject must search more slowly (and carefully!). To estimate more accurately the slowing of search, the effect of self-termination (Factor 6), which speeds the search for absence, was removed. The slowing of search in search for absence was found to involve nontarget letters as well as target letters and to involve the memory-comparison stage.     

Studying visual search using systems factorial methodology with target-distractor similarity as the factor

Systems factorial technology (SFT) is a theory-driven set of methodologies oriented toward identification of basic mechanisms, such as parallel versus serial processing, of perception and cognition. Studies employing SFT in visual search with small display sizes have repeatedly shown decisive evidence for parallel processing. The first strong evidence for serial processing was recently found in short-term memory search, using target-distractor (T-D) similarity as a key experimental variable (Townsend & Fifi?, 2004). One of the major goals of the present study was to employ T-D similarity in visual search to learn whether this mode of manipulating processing speed would affect the parallel versus serial issue in that domain. The result was a surprising and regular departure from ordinary parallel or serial processing. The most plausible account at present relies on the notion of positively interacting parallel channels.     

What research paradigms have cognitive psychologists used to study "false memory," and what are the implications of these choices?

This research examines the methodologies employed by cognitive psychologists to study "false memory," and assesses if these methodologies are likely to facilitate scientific progress or perhaps constrain the conclusions reached. A PsycINFO search of the empirical publications in cognitive psychology was conducted through January, 2004, using the subject heading, "false memory." The search produced 198 articles. Although there is an apparent false memory research bandwagon in cognitive psychology, with increasing numbers of studies published on this topic over the past decade, few researchers (only 13.1% of the articles) have studied false memory as the term was originally intended--to specifically refer to planting memory for an entirely new event that was never experienced in an individual's lifetime. Cognitive psychologists interested in conducting research relevant to assessing the authenticity of memories for child sexual abuse should consider the generalizability of their research to the planting of entirely new events in memory.     

The effect of perceptual distinctiveness on the prospective and retrospective components of prospective memory in young and old adults.

In two experiments, the effect of perceptual distinctiveness of cues on prospective memory performance was examined. Young and older adults completed a visual search task with embedded prospective memory instructions. On each trial, participants were asked to indicate the position of a target letter in a letter string, unless either of two letters previously identified as prospective memory cues was presented. Each prospective cue was associated with a specific response. Perceptual distinctiveness was manipulated by spatially displacing a single letter. The prospective component (successful detection of the cue) and the retrospective memory component (recalling the correct response when a cue is detected) were measured separately. Perceptual displacement of cues modulated performance of the prospective component but not the retrospective component. Young adults successfully detected a larger proportion of cues (prospective component) than older adults. However, there were minimal effects of age and no effect of cue displacement on participants' ability to recall the intention once they detected a cue (retrospective component performance). Results are discussed within the context of current theoretical models of prospective memory.     

Studying visual search using systems factorial methodology with target—distractor similarity as the factor

Systems factorial technology (SFT) is a theory-driven set of methodologies oriented toward identification of basic mechanisms, such as parallel versus serial processing, of perception and cognition. Studies employing SFT in visual search with small display sizes have repeatedly shown decisive evidence for parallel processing. The first strong evidence for serial processing was recently found in short-term memory search, using target-distractor (T-D) similarity as a key experimental variable (Townsend & Fifi?, 2004). One of the major goals of the present study was to employ T-D similarity in visual search to learn whether this mode of manipulating processing speed would affect the parallel versus serial issue in that domain. The result was a surprising and regular departure from ordinary parallel or serial processing. The most plausible account at present relies on the notion of positively interacting parallel channels.     

Longitudinal Changes in Memory Performance and Processing Speed in Old Age abstract Keywords

The speed theory of cognitive aging posits that an age-related slowing of processing speed leads to impairments in higher order cognitive functions, such as memory. However, only few studies have examined the relationship between longitudinal changes in processing speed and longitudinal changes in memory performance. In the present study, data of 474 older adults (T1: 59–65 years) from the Interdisciplinary Longitudinal Study on Adult Development (ILSE) were used to investigate whether changes in speed and in memory were associated over a 4-year period. Performance changes in both constructs were analyzed using latent change factor models. Results show that latent changes in processing speed and latent changes in memory performance correlated with 0.61. This association is considerably lower than what would have been expected from cross-sectional data. Our longitudinal results suggest that although speed changes explain a substantial proportion of variance in memory changes, additional explanatory factors must be taken into consideration.     

An analysis of age differences in perceptual speed

Tests of the generalized slowing hypothesis have demonstrated the strong predictive power of tests of perceptual comparison speed in accounting for age differences across a range of cognitive domains. The goals of this study were to determine whether short-term memory (STM) and perceptual demands contribute to age differences on two commonly used tests of perceptual comparison speed, the letter and pattern comparison tests, and to test whether these task components account for unique variance in predicting age differences in working memory and reasoning. Results showed that, after controlling for visual contrast sensitivity and a general slowing factor, age differences increased with increases in both STM load and perceptual degradation. Only STM load, however, accounted for a significant portion of the relationship of age with higher level cognition. We concluded that perceptual comparison tests are dependent on multiple age-sensitive abilities, not all of which are related to age differences in higher level cognition.     

Accuracy and speed strategies in scanning active memory

The effect of speed and accuracy payoff on performance in a short-term memory scanning task was investigated under two conditions of familiarity of material and two conditions of payoff. Memory sets and probes were either drawn from a small well learned pool of words (thefamiliar set) or were sampled without replacement from a very large pool of words (theinfinite set). Under both payoffs the infinite memory sets were searched at a faster rate than the familiar sets. The speed payoff reduced the constant component of latencies and, contrary to previous findings, increased the rate of memory search for both sets. Errors increased from about 1% with accuracy payoff to 19% with speed payoff. Under speed payoff most of the errors were false positives for the familiar set and false negatives for the infinite set. Several models of the task were considered, but none proved entirely satisfactory.     

Central executive system impairment in traumatic brain injury

The aim of the present study was to identify cognitive functions affected by traumatic brain injury (TBI) and to verify the mechanism underlying cognitive impairment. More precisely, cognitive deficits following TBI can be considered as a consequence of (a) a speed processing deficit, that is a general slowing of perceptual, motor and cognitive subroutines; (b) an impairment of the Central Executive System of working memory (CES).Thirty-seven patients were submitted to a neuropsychological battery, aimed to evaluate different cognitive functions.Results showed severe deficits in speed processing, divided attention,working memory, executive functions and long term memory.Regression analyses, performed to test the two hypotheses, showed that the working memory deficit hypothesis is able to explain divided attention, executive functions and long term memory deficits more than speed processing hypothesis.     

The influence of complex working memory span task administration methods on prediction of higher level cognition and metacognitive control of response times

Participants between the ages of 18 and 80 were tested on a complex working memory span task that was administered either using a typical experimenter-paced method or using a method in which the processing component was presented at a fixed, limited-pace presentation rate. Path analyses revealed that even after controlling for individual differences in general processing speed, the limited-pace task predicted unique variance in episodic memory, executive functioning, and fluid intelligence, whereas the experimenter-paced task did not. For the experimenter-paced task, slower responses on the processing component of the task were associated with better recall, but only when individual differences in processing speed were controlled. These findings suggest that metacognitive control of response times affects recall from working memory span tasks, as well as the relationship between span task recall and high-level cognition. These results support resource-sharing explanations of working memory and suggest that limiting processing times using computer pacing of complex span tasks can be an effective way to efficiently measure working memory capacity.     

Age-related deficits in generation and manipulation of mental images: I. The role of sensorimotor speed and working memory.

The authors investigated age-related slowing of information processing in mental imagery tasks. Eighty-five healthy adults (ages 18 to 77) performed a visual, sensorimotor, reaction-time task; a visual-perceptual choice reaction task; and 3 mental imagery tasks that varied in apparent difficulty and involved stimuli at 2 levels of graphic complexity. Age was associated with prolongation of response time across all tasks and both levels of stimulus complexity. Accuracy of response was adversely affected by increase in stimulus complexity in all tasks, whereas it was negatively related to age only on the tasks with substantial mental imagery requirements. Slowing of information processing and reduction in accuracy were mediated by declines in working memory but not by decrease of sensorimotor speed.     

The effects of delay and interference: A speed-accuracy study

This paper examines the effect of (1) delay between learning and test and (2) associative interference on memory retrieval speed. The speed-accuracy tradeoff methodology, which interrupts the retrieval process at various times (0.3, 0.7, 1.0, 1.5, 2.0, and 3.0 sec) after presentation of the test item, provides a means of separating retrieval speed effects from effects on overall memory strength. Performance at short processing times is an index of retrieval speed. Performance given ample processing time is a measure of asymptotic accuracy, or memory strength. Increasing the delay between learning and test or introduction of interference relations lowered memory trace strength, as reflected in asymptotic accuracy. Items tested shortly (about 3 sec) after learning showed a significant speedup in retrieval relative to items tested at a longer (several minute) delay. Further analysis suggested that the delay effect on retrieval was primarily the result of immediate repetition, or testing of the last-learned item. The interference manipulation showed a slight and nonsignificant tendency toward slowing of memory retrieval. The implications of these results for various models of retrieval are explored via simulations. The results of all the simulations suggested a direct-access retrieval process where associations are processed largely in parallel. Contradiction or mismatch information in recognizing new items was important because it provided an explanation for a slight slowing in retrieval due to interference even with a parallel-processing assumption. Faster retrieval for the last-learned item may be the result of residual activation following active processing.     

Aging and working memory inside and outside the focus of attention: dissociations of availability and accessibility

Two experiments used the N-Back task to test for age differences in working memory inside and outside the focus of attention. Manipulations of the difficulty of item-context binding (Experiment 1) and of stimulus feature binding (Experiment 2) were used to create conditions that varied in their demand on working memory, with the expectation that greater demand might increase age differences in focus-switching costs and the search rate outside the focus of attention. Results showed, however, that although age differences were evident in measures of overall speed and accuracy, and the manipulations significantly affected response times and accuracy in the expected direction, the experimental manipulations had no impact on age differences. Findings instead pointed to age-related reductions in accuracy but not speed of focus-switching and search outside the focus of attention. Thus, age-related deficits appear to involve the availability of representations in working memory, but not their accessibility.     

Google and the mind: predicting fluency with PageRank

Human memory and Internet search engines face a shared computational problem, needing to retrieve stored pieces of information in response to a query. We explored whether they employ similar solutions, testing whether we could predict human performance on a fluency task using PageRank, a component of the Google search engine. In this task, people were shown a letter of the alphabet and asked to name the first word beginning with that letter that came to mind. We show that PageRank, computed on a semantic network constructed from word-association data, outperformed word frequency and the number of words for which a word is named as an associate as a predictor of the words that people produced in this task. We identify two simple process models that could support this apparent correspondence between human memory and Internet search, and relate our results to previous rational models of memory.     

Balancing cognitive demands: control adjustments in the stop-signal paradigm

Cognitive control enables flexible interaction with a dynamic environment. In 2 experiments, the authors investigated control adjustments in the stop-signal paradigm, a procedure that requires balancing speed (going) and caution (stopping) in a dual-task environment. Focusing on the slowing of go reaction times after stop signals, the authors tested 5 competing hypotheses for post-stop-signal adjustments: goal priority, error detection, conflict monitoring, surprise, and memory. Reaction times increased after both successful and failed inhibition, consistent with the goal priority hypothesis and inconsistent with the error detection and conflict hypotheses. Post-stop-signal slowing was greater if the go task stimulus repeated on consecutive trials, suggesting a contribution of memory. We also found evidence for slowing based on more than the immediately preceding stop signal. Post-stop-signal slowing was greater when stop signals occurred more frequently (Experiment 1), inconsistent with the surprise hypothesis, and when inhibition failed more frequently (Experiment 2). This suggests that more global manipulations encompassing many trials affect post-stop-signal adjustments.     

Effort during visual search and counting: insights from pupillometry

We investigated the processing effort during visual search and counting tasks using a pupil dilation measure. Search difficulty was manipulated by varying the number of distractors as well as the heterogeneity of the distractors. More difficult visual search resulted in more pupil dilation than did less difficult search. These results confirm a link between effort and increased pupil dilation. The pupil dilated more during the counting task than during target-absent search, even though the displays were identical, and the two tasks were matched for reaction time. The moment-to-moment dilation pattern during search suggests little effort in the early stages, but increasingly more effort towards response, whereas the counting task involved an increased initial effort, which was sustained throughout the trial. These patterns can be interpreted in terms of the differential memory load for item locations in each task. In an additional experiment, increasing the spatial memory requirements of the search evoked a corresponding increase in pupil dilation.These results support the view that search tasks involve some, but limited, memory for item locations, and the effort associated with this memory load increases during the trials. In contrast, counting involves a heavy locational memory component from the start.     

Effort during visual search and counting: Insights from pupillometry

We investigated the processing effort during visual search and counting tasks using a pupil dilation measure. Search difficulty was manipulated by varying the number of distractors as well as the heterogeneity of the distractors. More difficult visual search resulted in more pupil dilation than did less difficult search. These results confirm a link between effort and increased pupil dilation. The pupil dilated more during the counting task than during target-absent search, even though the displays were identical, and the two tasks were matched for reaction time. The moment-to-moment dilation pattern during search suggests little effort in the early stages, but increasingly more effort towards response, whereas the counting task involved an increased initial effort, which was sustained throughout the trial. These patterns can be interpreted in terms of the differential memory load for item locations in each task. In an additional experiment, increasing the spatial memory requirements of the search evoked a corresponding increase in pupil dilation.These results support the view that search tasks involve some, but limited, memory for item locations, and the effort associated with this memory load increases during the trials. In contrast, counting involves a heavy locational memory component from the start.