Endothelin B receptor-mediated vasoconstriction induced by endothelin A receptor antagonist

BACKGROUND: Capacity limitation theories have proved to be surprisingly resilient in characterizing some of the cognitive deficits in schizophrenia. However, this perspective has not generally been applied to short-term verbal memory tasks. We explored this issue by first attempting to ascertain if gross misallocations of processing resources might explain impairments in short-term memory in schizophrenia on a classic digit span task and in a second study by attempting to determine what effects delay and memory set size had on a divided attention short-term verbal memory paradigm. METHODS: In the first study 16 patients with schizophrenia and 21 normal controls received 40 trials of a three digit task and 20 trials of a six digit span task. As the absolute number of digits presented and duration of presentation in two conditions were identical, subjects thus had equivalent 'opportunities' to make errors if distraction, in the sense of misallocation of cognitive resources, were at the root of poor performance. In the second study 15 patients with schizophrenia and 15 normal controls were tested in conditions in which two, four or six words were presented and in which rehearsal was prevented by an interference task (colour naming) for delays of 5, 10 or 15 s. RESULTS: Patients had disproportionate difficulty on the six digit rather than the three digit condition, suggesting that deficits in the verbal working memory short-term store may not be the result of attentional factors. In the second study, patients' performance was differentially worsened by the interference task, by memory set size (i.e. a capacity limitation) and by delay, a measure of decay rate. CONCLUSIONS: In concert, these studies demonstrate that schizophrenia patients have difficulties on verbal short-term memory span tasks not because of misallocation of resources, but rather because of limitations in 'representational capacity' and maintenance of information over delays.     

Tapping sensitivity to processing in short-term memory.

Examined the interference between finger tapping and searching in short-term memory (STM). 20 Ss (mean age 22.4 yrs) memorized a set of digits and then executed a series of 17 taps separated by 2 sec subjective time intervals. During each interval, a probe was presented for comparison with the items in the memory set. The amount of processing in STM was varied from series to series by manipulating the number of items in the memory set. Results show that mean duration and variability of intertap intervals increased proportionally with memory set size. This effect is explained as interference between STM processing and the timing component of the tapping performance. The authors suggest that tapping sensitivity to memory load indicates that, under some conditions, variations in tapping performance are valid indicators of STM processing requirements of a concurrent primary task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Depression in multiple sclerosis: Relationship to working memory capacity.

Recent research has shown that depression in multiple sclerosis (MS) is associated with deficits on cognitively demanding tasks. One explanation for this relationship is that depressed NIS patients may have reduced working memory capacity. The present study was designed to test this hypothesis. Depressed NIS patients were compared with nondepressed MS patients and nondepressed healthy controls on a task of working memory capacity (reading span) and a short-term memory task not taxing working memory capacity (word span). In support of the capacity-reduction model, compared with the nondepressed groups, depressed MS patients performed significantly worse on reading span but not on word span. Additionally, reading span was significantly correlated with capacity-demanding tasks shown to be impaired in depressed NIS patients in previous reports. Results suggest that depressed MS patients are characterized by limited working memory capacity and that the central executive component of the working memory system may be most affected. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The tongue-twister effect in reading Chinese.

Two studies demonstrate a visual tongue-twister effect (TTE) in Chinese and add support to the assumption that reading in any writing system engages a phonological memory system. Exp 1 showed that for both oral and silent reading, Ss took longer to read texts with repeated initial phonemes (IPs) than to read control stories with mixed IPs. Exp 2 verified the phonemic nature of the TTE in a dual task situation in which Ss had to retain a string of digits while reading a sentence. The results showed a specific-phoneme interference such that Ss took longer to read the texts when digits and words had the same IPs than when they had different phonemes. Both studies provide evidence that the source of the TTE in both Chinese and English is phonological interference rather than visual confusion. They confirm the highly general nature of phonological involvement in skilled sentence reading. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Category-order effects in memory span.

When Ss are required to recall lists containing both words and digits, memory span is higher when the digits precede the words than when the words precede the digits. In Exp 1, both forward and backward recall were tested; it was demonstrated that this category-order effect reflects the input position, and not the output position, of the items. Exp 2 revealed that this effect was not eliminated by a filled retention interval. Exp 3 showed that the effect was eliminated when lists were presented at a fast presentation rate. In Exp 4, the effect was eliminated when Ss engaged in articulatory suppression. A 5th experiment extended the findings of Exp 4 to the case in which lists are composed of semantically related or unrelated words. These results suggest that category-order effects reflect mnemonic activity that Ss engage in during list presentation and do not arise from structural characteristics of the memory system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is "working memory capacity" just another name for word knowledge?

This study is concerned with whether the correlation between complex working memory spans and reading comprehension occurs because the complex spans reflect the capacity of a structural working memory that plays a causal role in comprehension or because a 3rd factor, word knowledge, plays a causal role in both the span tasks and comprehension. If the latter hypothesis is correct, the correlation between word span and reading comprehension should be large when span is tested with low-frequency words but should not occur when span is tested with very familiar words. 90 college students were tested on a simple and a complex version of the word span task with high- and low-frequency words. The Verbal Scholastic Aptitude Test (VSAT) was used as a measure of reading comprehension. The correlation between span and VSAT was somewhat higher when span was tested with low-frequency words, but was significant with both low- and high-frequency words. This suggests that both word knowledge and a content-free working memory play a causal role in the relationship between word span and higher level cognitive tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correction to Emery, Hale, and Myerson (2008).

Reports an error in "Age differences in proactive interference, working memory, and abstract reasoning" by Lisa Emery, Sandra Hale and Joel Myerson (Psychology and Aging, 2008[Sep], Vol 23[3], 634-645). The original article contained an incorrect DOI. The correct DOI is as follows: 10.1037/a0012577. (The following abstract of the original article appeared in record 2008-13050-014.) It has been hypothesized that older adults are especially susceptible to proactive interference (PI) and that this may contribute to age differences in working memory performance. In young adults, individual differences in PI affect both working memory and reasoning ability, but the relations between PI, working memory, and reasoning in older adults have not been examined. In the current study, young, old, and very old adults performed a modified operation span task that induced several cycles of PI buildup and release as well as two tests of abstract reasoning ability. Age differences in working memory scores increased as PI built up, consistent with the hypothesis that older adults are more susceptible to PI, but both young and older adults showed complete release from PI. Young adults' reasoning ability was best predicted by working memory performance under high PI conditions, replicating M. Bunting (2006). In contrast, older adults' reasoning ability was best predicted by their working memory performance under low PI conditions, thereby raising questions regarding the general role of susceptibility to PI in differences in higher cognitive function among older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term memory impairment and arithmetical ability

We document the dissociation of preserved calculation skills in a patient with impaired auditory short-term memory. The patient (MRF) had a memory span of three digits. Furthermore, he showed rapid decrement in performance of single digits and letters with both auditory and visual presentation in the Brown-Peterson forgetting task. Analysis of his calculation skills revealed a normal ability to solve auditorily presented multidigit addition and subtraction problems such as 173 + 68 and to execute the Paced Auditory Serial Addition Task (Sampson, 1956, 1958; Gronwall, 1977). In addition, his performance on other tests, including arithmetic manipulation of natural numbers, decimals and fractions, approximation, magnitude, ratio, and percentage, appeared to be normal (Hitch, 1978b). It is argued that these findings require a revision of Baddeley and Hitch's (1974) concept of the function of working memory.     

The role of spatial working memory in inhibition of return: evidence from divided attention tasks

Inhibition of return (IOR) refers to a bias against returning attention to a location that has been recently attended. In the present experiments, we examined the role of working memory in IOR by introducing secondary tasks (in the temporal interval between the cue and the target) that involved a working memory component. When the secondary task was nonspatial in nature (monitoring odd digits or adding digits), IOR was present, although overall reaction times were greater in the presence of the secondary task. When the task involved a spatial working memory load (remembering the directionality of arrows or the orientation of objects), IOR was eliminated. However, when the participants had incentive to process the directionality of an arrow but did not have to use any memory system, IOR persisted at peripheral locations. Overall, the results suggest that IOR is partially mediated by a spatial working memory system.     

Investigation of functional working memory in the reading span test.

Two issues were investigated in 2 experiments: (1) the validity of a reading span test that combined a knowledge verification task with a secondary task of word memorization and (2) the hypothesis that word recall reflects the amount of working memory that is functional in reading. In Exp 1, the validity and reliability of the reading span measure were determined. In Exp 2, it was reasoned that if word recall reflected functional working memory in reading, then 2 results should be observed. The 1st predicted result was that prior exposure to sentences used in the reading span test would release working memory resources and improve word recall. The 2nd was that word recall, though correlated with general working memory and verbal knowledge measures, would add to these scores in predicting comprehension. Both sets of results were obtained, supporting the hypothesis that the reading span test measures functional working memory in reading. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of neonatal dopamine depletion on spatial ability during ontogeny.

Investigated the effects of neonatal dopamine (DA) depletion on spatial discrimination tasks. Ss were lesioned at 3 and 6 days of age with intraventricular 6-hydroxydopamine preceded by Desipramine. In Exp 1, Ss were tested before weaning for the ability to spontaneously alternate in a T maze both in the presence of their home cage shavings and with a screen covering the shavings. Lesioned Ss were significantly impaired in their ability to spontaneously alternate. Control and lesioned Ss both showed a decrease in performance when the screen prevented full access to the shavings and the magnitude of the impairment was significantly greater for the lesioned animals. In Exp 2, Ss were tested after weaning in an appetitively motivated task in T maze. The task required both a functional working and reference memory. Lesioned Ss were impaired on both the working and the reference components of the task; however, the magnitude of the impairment was greater in the working memory task. Results suggest that early lesions of general DA systems produce deficits in tasks requiring spatial alternation behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of low-intensity hippocampal stimulation on spatial versus working memory in rats.

Investigated differing predictions from the spatial mapping hypothesis of hippocampal function proposed by O'Keefe and Nadel (1978) and the working memory hypothesis proposed more recently by Olton and colleagues (Olton, Becker, & Handelmann, 1979). Each of 2 groups of rats was trained to use a different strategy to locate a submerged platform in opaque water. The MAP group used a spatial mapping strategy to reach a platform in a fixed location, whereas the CUE group used a guidance strategy, which involved following a cue that signaled the location of a randomly placed platform. Half of each group was given low-level unilateral electrical stimulation of the dentate gyrus and immediately tested on the water maze task. Results of Exp 1 show that both the MAP and CUE groups were impaired by stimulation. However, there was an inadvertent spatial element involved in the CUE task. When this element was eliminated in Exp 3, the same CUE Ss were unaffected by a 2nd series of stimulation trials, whereas the MAP Ss continued to show impairment. Results strongly support the cognitive mapping hypothesis and provide little support for the working memory hypothesis of hippocampal function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Pessimistic noise effects": The perception of reaction times in noise.

Used a between-group design to examine the effect of loud noise on a 2-choice discrete reaction task and the judgments Ss made about self-produced RTs under these conditions. In Exp I, 70 Ss (aged 26–39 yrs) completed a 2-choice RT task and a concurrent RT rating task of speed. White noise was presented to Ss in the experimental groups. RTs were unexpectedly faster in noise, but Ss used more "slow" categories in describing them. The effect was not apparent when the same RTs were rerated a 2nd time under instructions that indicated that they were random time intervals. Also, the effect was not apparent when a new group of 14 undergraduates in Exp II rated the original RT data, again in noise. Exp III showed that when asked to predict average RTs produced by a hypothetical S in noise, 30 uniformed Ss (aged 26–39 yrs) predicted slow RTs. Results are considered in the light of the hypothesis that pessimistic expectancies about likely effects of noise may be a factor influencing performance. (French abstract) (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Proactive interference in short-term retention of human faces.

Tested whether release from proactive interference occurs in short-term recognition memory following a shift in the learning of male faces to the learning of female faces, and vice versa. Ss were 52 female and 52 male college students. Proactive interference was found to increase over 4 successive study-test trials and a significant release effect was obtained on Trial 5. Female faces were more difficult to recognize than male faces after a build-up of proactive interference, suggesting that differential interference for sex attributes had occurred. No differences were found between male and female Ss in the release effect, but female Ss were superior to males on Trials 1-4. Results are discussed in terms of the influence of motivation on memory for faces as well as supporting a theory of visual short-term memory. (French summary) (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The suffix effect and preattentive unit-formation in visual short-term memory.

Tested immediate ordered recall of digits from visual short-term memory (STM) using a long-exposure visual presentation during which Ss spoke aloud. 24 college students served in each of 3 experiments. A to-be-ignored digit placed to the right of the visual presentation, called a suffix, impaired recall approximately 1 digit, suggesting that the suffix could not be excluded from visual STM. The suffix effect was attenuated when the suffix was segregated from the to-be-recalled digits by Gestalt principles of grouping, suggesting that a segregated suffix could be excluded from visual STM. Results indicate that the visual field is organized into units preattentively according to Gestalt principles of grouping and that when a unit (such as a string of digits) is selected, the entire unit enters visual STM. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Impact of Order Incongruence Between a Task-Irrelevant Auditory Sequence and a Task-Relevant Visual Sequence.

A novel effect is reported in which serial recall of visual digits was disrupted to a greater degree by the presence of the same set of digits presented as an irrelevant auditory sequence than by the presence of irrelevant auditory consonants, but only when the order of the irrelevant digits was incongruent with that of the to-be-remembered digits (Experiment 1). Experiment 2 replicated this order-incongruence effect and showed also that disruption was dictated by the number of order-incongruent transitions but not by the number of novel tokens contained within the irrelevant sequence. The results favor an interference-by- process approach to the disruption of serial memory by irrelevant sound over approaches based on notions of interference by content and/or interference by depletion of attentional resources. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive interference and learned helplessness: The effects of off-task cognitions on performance following unsolvable problems.

Assessed the effects of individuals' proneness to cognitive interference on performance following failure. Ss responded to a questionnaire tapping proneness to cognitive interference and were exposed to either no feedback or failure. On completing these problems, Ss performed a cognitive task in which the memory load was varied systematically. The cognitive interference theory successfully predicted most of the group differences: (a) Only the performance of Ss with a habitual tendency to engage in off-task cognitions was debilitated by failure; (b) this performance impairment was only observed in performance accuracy in the high memory load version of the task; and (c) performance accuracy was associated with the frequency of off-task cognitions in the experiment. Results were discussed in terms of the cognitive interference interpretation of learned helplessness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Processing acoustically presented time intervals of seconds duration: an expression of the phonological loop of the working memory?

Working memory has been proposed to contribute to the processing of time, rhythm and music; the question which component of working memory is involved is under discussion. The present study tests the hypothesis that the phonological loop component (Baddeley, 1986) is involved in the processing of auditorily presented time intervals of a few seconds' duration. Typical effects well known with short-term retention of verbal material could be replicated with short-term retention of temporal intervals: The immediate reproduction of time intervals was impaired under conditions of background music and articulatory suppression. Neither the accuracy nor the speed of responses in a (non-phonological) mental rotation task were diminished under these conditions. Processing of auditorily presented time intervals seems to be constrained by the capacity of the phonological loop: The immediate serial recall of sequences of time intervals was shown to be related to the immediate serial recall of words (memory span). The results confirm the notion that working memory resources, and especially the phonological loop component, underlie the processing of auditorily presented temporal information with a duration of a few seconds.     

Verbal and spatial working memory in school-age children: Developmental differences in susceptibility to interference.

The development of verbal and spatial working memory was investigated with an interference paradigm. Memory spans were obtained from 3 groups (8-, 10-, and 19-yr olds) under 6 different conditions: Two primary memory tasks (1 verbal, 1 spatial) were administered in isolation and in conjunction with 2 versions of a secondary task. The primary tasks required recalling a series of visually presented digits and recalling the locations of Xs in a series of visually presented grids. The secondary tasks required reporting the color of the stimuli as they were presented using either a verbal or a spatial response. Analyses revealed that all age groups showed domain-specific interference (i.e., interference by a secondary task from the same domain as the primary task), but only the 8-yr-olds also showed nonspecific interference (i.e., interference by a secondary task from a domain different than the primary memory task), suggesting that at least some executive functions do not reach adult levels of efficiency until approximately age 10. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Proactive interference and item similarity in working memory.

Proactive interference (PI) may influence the predictive utility of working memory span tasks. Participants in one experiment (N=70) completed Ravens Advanced Progressive Matrices (RAPM) and multiple versions of operation span and probed recall, modified for the type of memoranda (digits or words). Changing memoranda within- or across-trials released PI, but not doing so permitted PI buildup. Scores from PI-build trials, but not PI-release trials, correlated with RAPM and accounted for as much variance in RAPM as unmodified tasks. These results are consistent with controlled attention and inhibition accounts of working memory, and they elucidate a fundamental component of working memory span tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)