Biomedical subjects

D L Strayer

Publications and source records attributed to D L Strayer.

18 recordsLinked to original sources

PubMed2001

Further evidence of intact working memory in autism.

Earlier investigations have found mixed evidence of working memory impairment in autism. The present study examined working memory in a high-functioning autistic sample, relative to both a clinical control group diagnosed with Tourette Syndrome and a typically developing control group. No group differences were found across three tasks and five dependent measures of working memory. Performance was significantly correlated with both age and IQ. It is concluded that working memory is not one of the executive functions that is seriously impaired in autism. We also suggest that the format of administration of working memory tasks may be important in determining whether or not performance falls in the impaired range.

Adolescent↗

PubMed2000

Novel popout is an attention-based phenomenon: an ERP analysis.

When observers are given a brief glimpse of a display containing one novel object and three repeated objects, they are often better able to report the location of the novel object than the location of any one of the repeated objects. The present study contrasted two interpretations of this "novel popout" effect. The attention-based interpretation suggests that the novel popout is an attentional phenomenon, occurring during the initial processing of the four-object display. The retrieval-based interpretation suggests that novel popout is due to differential processing occurring when observers are subsequently probed for the location of one of the objects in the display. ERP measures recorded while subjects performed the novel popout task revealed differences during the initial processing of the four-object display but not subsequent to the presentation of a localization probe. The findings are most consistent with the attention-based interpretation of novel popout, which suggests that attention is rapidly drawn to the novel object in an otherwise familiar display.

Adolescent↗

PubMed1999

Negative identity priming is contingent on stimulus repetition.

Five experiments demonstrate that negative identity priming is contingent on stimulus repetition. In ignored repetition conditions, priming was initially positive and became negative as the number of repetitions increased. Moreover, it was repetition as a target, not as a distractor, that was critical for negative priming. The effects of repetition were general: They were found with both naming and same-different paradigms, verbal and pictorial material, familiar and unfamiliar stimuli, and vocal and manual responses. Findings support an activation-based model of negative priming (G. B. Malley & D. L. Strayer, 1995) and are problematic for the episodic retrieval model of negative priming (W. T. Neill & L. A. Valdes, 1992). Finally, the experiments did not replicate B. DeSchepper and A. Treisman's (1996) reported negative priming with nonrepeated novel shapes.

Adolescent↗

PubMed1998

Inhibitory deficits in Tourette syndrome: a function of comorbidity and symptom severity.

This study examined central inhibitory function in children with Tourette syndrome (TS; N = 46) and normally developing controls (N = 22) matched on age, gender, and IQ. A negative priming task measured the ability to inhibit processing of irrelevant distractor stimuli presented on a visual display. Initial analyses indicated that participants with Tourette syndrome did not differ significantly in inhibitory function from controls. However, when the large Tourette syndrome sample was separated into subgroups, one without evidence of comorbidity (N = 23) and the other meeting research criteria for either AD/HD, OCD, or both (N = 23), it became evident that individuals with Tourette syndrome with comorbid conditions tended to perform less well than the control group, whereas those without comorbidity performed much like controls. Similarly, when the large Tourette syndrome sample was divided into two subgroups on the basis of severity of symptomatology (N = 23 in each), those with more numerous and severe symptoms of Tourette syndrome, AD/HD, and OCD performed significantly less well than both controls and Tourette syndrome subjects with fewer and less severe symptoms. This suggests that neuropsychological impairment occurs as a function of comorbidity and symptom severity in Tourette syndrome. It also suggests that categorical diagnoses alone may be less useful than dimensional methods for predicting cognitive impairment in individuals with Tourette syndrome.

Adolescent↗

PubMed1997

Inhibitory function in nonretarded children with autism.

This study examined inhibitory function in nonretarded children with autism (n = 13) and normally developing controls (n = 13) matched on age and IQ. Tasks measuring motor and cognitive components of inhibition were administered to both groups. On the Stop-Signal paradigm, children with autism were able to inhibit motor responses to neutral and prepotent stimuli as well as control subjects. On the Negative Priming task, the groups were equally capable of inhibiting processing of irrelevant distractor stimuli in a visual display. Results suggest that at least two components of inhibition are spared in individuals with autism, standing in contrast to flexibility and other executive deficits that have been found in previous studies. These findings may help distinguish children with autism from those with other neurodevelopmental conditions that involve executive dysfunction.

Adolescent↗

PubMed1997

Testing race models of visual search.

Race models of visual search make specific predictions about the nature of the speed-up in search performance as the number of stimulus features cuing the spatial location of a target increases. First, both the reaction time (RT) mean and standard deviation must decrease as a power function of the number of stimulus dimensions specifying a target location. Second, the rate parameter of these two power functions must be equivalent. Finally, the shape of the entire RT distribution must be determined by the same factors that determine the shape of the power functions. Two experiments are presented that provide strong support for these predictions.

Adolescent↗

PubMed1995

Effect of stimulus repetition on positive and negative identity priming.

Most negative-priming experiments have used a limited number of stimuli that are repeated many times throughout the experiment. We report five experiments that examine in greater detail the role of stimulus repetition in negative priming. Subjects were presented with displays consisting of two or more words, and were required to name the word printed in red. On attended repetition (AR) trials, the target word was the same as the target word on the preceding trial. On ignored repetition (IR) trials, the target word was the same as the distractor word on the preceding trial. Experiments 1 and 2 used novel words, and obtained positive priming on AR trials, but no negative priming on IR trials. Experiments 3 and 4 used repeated words, and obtained negative priming on IR trials, but no positive priming on AR trials. In Experiment 5, both novel and repeated words were intermixed, and negative priming was observed for repeated, but not novel, IR conditions, whereas positive priming was observed for novel, but not repeated, AR conditions. Together, Experiments 1-5 demonstrate that positive and negative identity priming are modulated by stimulus repetition and are stimulus specific.

Adolescent↗

PubMed1994

Aging and skill acquisition: learning-performance distinctions.

This research examined the hypothesis that a conservative response bias in older persons interferes with the acquisition and mastery of cognitive skill. Twenty younger and 20 older Ss performed both consistent mapping and varied mapping versions of a memory search task. Half of the Ss in each group performed under speed stress instructions, whereas the remaining Ss performed under accuracy stress instructions. Older Ss exhibited less skilled performance than did younger Ss. A power function analysis attributed this to both age-related differences in the rate of associative learning and differences in asymptotic levels of performance. These results are at odds with A. D. Fisk and W. A. Roger's (1991) hypothesis that age-related differences in automatization do not occur in memory search tasks. Results are interpreted in terms of a learning vs. performance distinction.

Adolescent↗

PubMed1994

Executive function abilities in autism and Tourette syndrome: an information processing approach.

This study used information processing paradigms to provide a detailed examination of executive function abilities in autism. The performance of non-retarded autistic children was compared with that of two matched control groups, one with Tourette Syndrome and the other developmentally normal. Autistic subjects performed as well as controls on tasks requiring global-local processing and inhibition of neutral responses. In contrast to both control groups, however, the autistic sample was significantly impaired on a measure of cognitive flexibility. The performance of children with Tourette Syndrome did not differ from that of normal controls on any task. These results refine our knowledge about executive dysfunction in autism and suggest a new conceptual framework and general method for investigating the cognitive underpinnings of neurodevelopmental disorders.

Adolescent↗

PubMed1994

Aging and inhibition: beyond a unitary view of inhibitory processing in attention.

The authors examined the question of whether a decrease in the efficiency of inhibitory processing with aging is a general phenomenon. Thirty elderly and 32 young adults performed a series of tasks from which the authors could extract measures of inhibitory function. The tasks and task components included response compatibility, negative priming, stopping, spatial precuing, Wisconsin Card Sorting Test (WCST), and the Cognitive Failures Questionnaire (CFQ). Only limited evidence for age-related differences in inhibitory function was obtained. Old adults had more difficulty than young adults in stopping an overt response and adopting new rules in a categorization task. However, elderly and young adults produced equivalent negative priming effects, response compatibility effects, spatial precuing effects, and self-reported cognitive failures. The findings are discussed in terms of the relationship between aging, inhibitory processes, and neuroanatomical and physiological function.

Adolescent↗

PubMed1993

Assessment of pilot performance and mental workload in rotary wing aircraft.

This research examined the processing demands imposed upon experienced pilots by two different communication formats, digital and verbal, in a high fidelity simulation of an advanced multi-function helicopter. The mental workload imposed by the type and magnitude of communications was assessed by a battery of subjective, performance, secondary, and physiological measures. The performance data indicated that the pilots had difficulty adhering to the Nap of the Earth altitude criterion with high communication demands, particularly with the digital communication system. This was presumably due to the requirement to spend more time scanning the multi-function displays with the digital than with the verbal communication system. On the other hand, the pilots were less prone to task shedding when they used the digital communication system possibly due to the provision of a permanent list of queries that was unavailable with the verbal system. Measures of heart rate variability and blink rate were larger with the verbal than with the digital system, presumably reflecting increased respiratory demands in the verbal condition as well as increased visual processing demands with the digital format. Finally, the probe evoked P300 component decreased in amplitude as a function of increases in the magnitude of communications. The results are discussed in terms of the structural and capacity demands of the communications systems that were proposed for the advanced multi-function helicopter.

Adult↗

PubMed1993

Cognitive function at high altitude.

The effects of altitude on human performance and cognition were evaluated in a field study performed on Mount Denali in Alaska during the summer of 1990. Climbers performed a series of perceptual, cognitive, and sensory-motor tasks before, during, and after climbing the West Buttress route on Denali. Relative to a matched control group that performed the tasks at sea level, the climbers showed deficits of learning and retention in perceptual and memory tasks. Furthermore, climbers performed more slowly on most tasks than did the control group, suggesting long-term deficits that may be attributed to repeated forays to high altitudes.

Adult↗

PubMed1992

Event related potentials and EEG components in a semantic memory search task.

This study examined the effects of memory search and related processes on both time and frequency domain components of electroencephalographic activity. More specifically, we were interested in the relationship between EEG and event-related potential (ERP) components as a function of memory load and response type. Subjects performed a semantic memory search task in which they matched word probes to category labels. Consistent with previous studies, reaction time increased and accuracy decreased with increasing memory loads. A negative component of the ERP (N400) was found to reflect semantic mismatch: N400s were larger for the nontargets than for the targets. Two ERP components were found to be reciprocally related to memory load. P300 decreased and Negative Slow Wave increased in amplitude with increases in the size of the memory set. These two ERP components were reflected by different components in a Principal Components Analysis. The power in the theta band (5-7 Hz) also increased as a function of memory load and appears to be functionally and topographically related to the Negative Slow Wave in the ERP. It is argued that both measures are jointly determined and reflect the difficulty of the conceptual operations during memory search.

Adult↗

PubMed1991

Task versus component consistency in the development of automatic processing: a psychophysiological assessment.

A study was conducted to examine the role of consistency in the development of automatic processing. Subjects performed a memory search task in which consistent and inconsistent attending and responding were factorially combined. The task was performed with memory set sizes of two and four items. Results indicated that automaticity developed with consistent attending regardless of whether responding was consistent or inconsistent. However, measures of reaction time, P300 latency, and P300 amplitude revealed costs for inconsistent responding that were attributed to both stimulus evaluation and response related processes. The results suggest that total task consistency is not necessary for the development of automatic processing. Instead, it appears that automaticity can develop for consistent task components even when stimulus-response consistency is not maintained across the entire task.

Adolescent↗

PubMed1990

Development and transfer of automatic processing.

Two studies were performed to examine the role of consistency in the development and transfer of automatic processing. Ss performed a rule-based memory search task in which they compared multidimensional probes to 1, 2, or 3 memory set rules. Results indicated that learning occurred in the absence of consistency at lower levels of task description (e.g., mapping of individual task components to responses) as long as higher level consistencies existed in the task (e.g., consistent) mapping of task components to a conceptual framework). However, the asymptotic level of this learning was modulated by the consistency with which conjunctions of task components were mapped to decisions. High positive transfer was obtained despite replacement of the exemplars of the memory set rules, suggesting that learning was not specific to the items encountered during training. On the other hand, the magnitude of positive transfer was reduced when the rules were replaced, suggesting that most of the learning took place at the level of specific rules. Some evidence was also obtained for more general process-based learning. Results are discussed in terms of their implications for models of learning and transfer.

Adolescent↗

PubMed1990

An analysis of memory-based theories of automaticity.

Memory-based theories of automaticity predict that performance in a memory search task which is automatic will not require a representation of the memory set in working memory. The information contained in working memory was manipulated by inserting an interference task between the presentation of a memory set and a probe stimulus in a memory search task. The interference task prevented rehearsal, necessitating the retrieval of the memory set from long-term memory in variably mapped (VM) conditions. Performance in consistently mapped (CM) conditions provided strong support for memory-based theories of automaticity. With CM practice, both the effects of memory load and the effect of the interference task were eliminated. Furthermore, there was a temporal coupling in the reduction of these two effects with consistent practice. Monte Carlo simulations of memory-based automaticity predict such a temporal coupling. Automaticity is viewed as a continuum reflecting the relative contribution of the direct memory access of past solutions from long-term memory on performance.

Adolescent↗

PubMed1988

Assessing the development of automatic processing: an application of dual-task and event-related brain potential methodologies.

Previous research has found that properties of automatic processing do not always co-occur, suggesting that the acquisition rates may differ. The present study investigated the acquisition rate of several of these properties by employing additive factors logic, dual task methodology, and event-related brain potentials. Seven subjects participated in a ten session experiment in which they performed two tasks, a visual/memory search task and a pursuit step tracking task, both together and separately. RT and P300 latency measures indicated that parallel processing of the display was achieved early in training in the consistent mapping condition. This processing was unaffected by dual task demands. An analysis of RT/P300 ratios suggests that another form of perceptual efficiency was achieved later in practice in both the varied and consistently mapped search tasks. This effect was larger in the consistent mapping condition. Reductions in the slope of the memory set function occurred significantly earlier for P300 latency than for RT, suggesting that the stimulus evaluation processes became automated more rapidly than the response selection components of memory search. Consistent with an analysis of the processing demands of the two tasks, the introduction of the tracking task and an increase in tracking difficulty produced equivalent interference during consistent and varied mapping conditions. Results are discussed in terms of models of skill, skill acquisition and component task automaticity.

Adult↗

PubMed1987

Adult age differences in the speed and capacity of information processing: 2. An electrophysiological approach.

A total of 60 subjects performed different variants of the Sternberg memory search task in an experiment designed to evaluate aging differences in the speed of the human information-processing system. The present study examined the nature of the age-related slowing using convergent methodologies of Sternberg's additive factors logic, the speed-accuracy trade-off, and the P300 component of the event-related brain potential. These methodologies revealed that a substantial component of slowing was manifest in perceptual encoding, response criterion adjustment, and response execution, with a lesser component related to memory search speed.

Adult↗