Biomedical subjects

Steven P Verney

Publications and source records attributed to Steven P Verney.

5 recordsLinked to original sources

PubMed2006

Effortful cognitive resource allocation and negative symptom severity in chronic schizophrenia.

BACKGROUND: The relationship between negative symptoms, early visual information-processing deficits, and effortful processing resource allocation was investigated. METHODS: Older patients with chronic schizophrenia (n = 58) and healthy controls (n = 71) participated. Pupillary responses were recorded during performance of the span of apprehension task (blocks of 3- and 10-letter arrays) as an index of resource allocation or mental effort during the task. RESULTS: Patients and controls showed larger pupillary responses in higher relative to lower processing loads both during array processing and just prior to array onset (preparation). Both groups, therefore, invested more cognitive effort preparing for and then processing larger arrays. A subgroup of patients with abnormally small pupillary responses and impaired performance showed greater negative symptom severity relative to a subgroup of patients with normal pupillary responses. Smaller pupillary responses in the patients were also significantly correlated with greater negative symptom severity, independent of positive symptom severity. Patients with reduced effortful resource allocation, therefore, exhibited greater negative symptomatology. A subgroup of patients with normal pupillary responses still showed impaired detection accuracy relative to controls, suggesting that reduced cognitive effort or resource allocation problems cannot account for impairments in early visual information processing in this subgroup. CONCLUSIONS: The study illustrates important relationships between cognitive effort and performance that can impact conclusions about the nature of cognitive impairments and associations between negative symptoms and neurocognition in schizophrenia.

Adult↗

PubMed2005

Culture-fair cognitive ability assessment: information processing and psychophysiological approaches.

Valid assessment with diverse populations requires tools that are not influenced by cultural elements. This study investigated the relationships between culture, information processing efficiency, and general cognitive capacities in samples of Caucasian and Mexican American college students. Consistent with the neural efficiency hypothesis, pupillary responses (indexing mental effort) and detection accuracy scores on a visual backward-masking task were both significantly related to the Wechsler Adult Intelligence Scale-Revised (WAIS-R) Full Scale scores. These measures of information processing efficiency were similar in the two groups. However, they were related only to Caucasian American, but not to a comparable sample of Mexican American, students' WAIS-R scores. Therefore, the differential validity in prediction suggests that the WAIS-R test may contain cultural influences that reduce the validity of the WAIS-R as a measure of cognitive ability for Mexican American students. Information processing and psychophysiological approaches may be helpful in developing culture-fair cognitive ability measures.

Adolescent↗

PubMed2004

Pupillary responses on the visual backward masking task reflect general cognitive ability.

Cognitive processing efficiency requires both an ability to attend to task-relevant stimuli with quickness and accuracy, also while filtering distracting or task-irrelevant stimuli. This study investigated cognitive processing efficiency by using pupillary responses as an index of attentional allocation to relevant target and irrelevant masks on a visual backward masking task. The relationship between attentional allocation on this task and general cognitive ability on the scholastic aptitude test (SAT) was examined in college students (n=67). A principle components analysis of the pupillary response waveform isolated a late component that appeared to index the attentional demands associated with processing masks on the backward masking task. This pupillary response index of wasteful resource allocation to the mask accounted for significant variance in SAT scores over and above that accounted for by socio-economic status and target detection accuracy scores. Consistent with the neural efficiency hypothesis, individuals who allocated more resources to processing irrelevant information performed more poorly on cognitive ability tests.

Adult↗

PubMed2004

Pupillary responses and attentional allocation problems on the backward masking task in schizophrenia.

Early visual information processing impairment has consistently been found on the backward masking task in patients with schizophrenia, but the nature of this impairment remains unclear. Pupillometry was used to measure attentional allocation during visual backward masking task performance in patients with schizophrenia (n=16) and nonpsychiatric controls (n=16). The extent of pupil dilation recorded during a cognitive task reflects the processing load placed on the nervous system by the task. Schizophrenia patients detected significantly fewer targets than controls only when the stimulus onset asynchrony (SOA) between targets and masks reached 317 ms. For both groups, peak pupil dilation responses were also significantly larger in the 317 ms SOA condition relative to a no-mask condition, suggesting that the processing load of the 317 SOA masking condition was greater than the no-mask condition. In addition, a principal components analysis of pupillary response waveforms identified time-related factors that appeared to differentially index attentional allocation to targets vs. masks. Patients with schizophrenia showed less dilation than controls on a middle factor that appeared to index attentional allocation to targets, but patients showed greater dilation than controls on a late factor that appeared to index attentional allocation to masks. That is, controls attended more to targets than to masks, but patients attended more to masks than to targets. These findings suggest that masking impairments at SOA intervals greater than 100-200 ms may be due abnormalities in attentional allocation mechanisms.

Attention↗

PubMed2003

Error-rate-related caudate and parietal cortex activation during decision making.

The role of cortical and subcortical structures in processing success or failure in decision-making situations is unclear. Functional neuroimaging (fMRI) during a two-choice prediction task was used to investigate the relationship between error-rate-related behavioral changes during decision-making and activation patterns in the caudate and parietal cortex. Success-related activation was found in caudate and parietal cortex during a two-choice prediction task. At low error rates, participants utilized success-related behavioral strategies rate by decreasing switching responses and increasing response predictability, which were associated with activation changes in the caudate and parietal cortex. Therefore, less response switching and increased response predictability during decision making can be directly related to the degree of activation in the caudate and posterior parietal cortex.

Adult↗