Using a laboratory computer for identification of nonlinear behavioral and electrophysiological systems

A system for mathematically identifying unknown nonlinear systems based upon Wiener kernels and G-functionals is presented as an example of the sophisticated analyses of electrophysiological and behavioral data made possible by the introduction of powerful digital computers to the laboratory environment. The applicability of these methods to a wide variety of systems is emphasized. By measuring the response of the unknown system to appropriate white noise stimulation, data may be obtained which are sufficient for the characterization of the system under test. The only restrictions upon the unknown system is that it be approximately stationary during the period of measurement and that its output depend upon its input in the finite past. Various pretests to evaluate the applicability of the method are presented. Simple FORTRAN programs that clarify the methods of computation are given for the preprocessing of data, the analysis of lower-order kernels, the synthesis of system response from the computed kernels, and the computation of the proportion of the variance in the systems output which is accounted for by the kernels zero, one, and two. These programs may be implemented on a digital laboratory computer of moderate size. Analysis may be performed either on-line or after data collection, depending upon the temporal characteristics of the system under test. This method represents one of the few analytical techniques presently available for the characterization of both linear and nonlinear systems. For this reason, it constitutes a uniquely powerful tool for many branches of psychology. Successful applications of this method to electrophysiological and behavioral data are mentioned. Limiting factors in the use of Wiener kernel analysis are also discussed.     

Sociodemographic Variations in Self-Reported Racism in a Community Sample of Blacks and Latino(a)s

This study investigated dimensions of socioeconomic status (SES) and self-reported racism among a convenience sample of 418 U.S.-born, Black and Latino(a) urban-dwelling adults. Predictors included indexes of individual and neighborhood SES. Self-reported racism was assessed with the Perceived Ethnic Discrimination Questionnaire–Community Version. Individuals at all levels of SES report racism, but the type of exposure varies by SES. Lower levels of SES predict higher levels of lifetime exposure to race-related stigmatization and threat/harassment, and more past-week discrimination. In contrast, higher levels of SES predict greater workplace discrimination. The findings highlight the importance of considering the complex ways in which SES and racism, 2 contributors to racial disparities in health, overlap and diverge.     

Spectrum Analysis of Cortical Activity During Verbal Planning: Physical Evidence for the Formation of Social Interaction Routines

A substantial body of scholarship focused on the processes involved in message planning has accumulated in the communication literature. One of the central tenets of memory models upon which most of the message planning models are based is that dynamic memory systems organize and reorganize knowledge structures to maximize information processing efficiency. Accordingly, efficiency can be achieved by merely retrieving and enacting plans that have achieved goals previously under similar conditions. Plan failure, however, requires alteration or even production of an original plan. Although researchers have relied exclusively on output (e.g., response latency, memory tests) to draw inferences about planning processes, it is possible to observe cognitive processes more directly by measuring cortical responses. In the present study, electrical activity was monitored in the region of the dorsolateral prefrontal cortex during verbal planning. Results indicated that (a) electrical activity while planning under conditions that permitted enactment of verbal plans that required no modification was significantly lower than during planning in the initial trial but, (b) electrical activity while planning under conditions in which previous efforts failed was significantly higher than during planning in the initial trial. These results provide physical evidence for the hypothetical cognitive processes proposed in the cognitivist models of routine formation.     

Cognitive Function in Parkinson's Disease: Association with Anxiety but Not Depression

To reexamine the relationships of depression, anxiety and cognitive impairment in Parkinson's disease (PD), 27 patients with idiopathic PD received two measures of depression, the State-Trait Anxiety Inventory, and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Contrary to some earlier studies, measures of depression, even those that separated mood from somatic symptoms, were not correlated with any measure of cognitive performance. By contrast, measures of anxiety were signifiantly and negatively correlated with all RBANS indexes. Because anxiety and depression are partially overlapping psychiatric disorders, inconsistent reports concerning the relationship of depression and cognition in PD may have arisen because different studies included varying proportions of depressed patients who were also highly anxious.     

Monitoring the Changing Status of Semantic Memory in Alzheimer's Disease: An Evaluation of Several Process Measures

The deficits in generating correct words on verbal fluency tasks exhibited by patients with Alzheimer's disease (AD) are accompanied by fewer switching responses, smaller phonemic and semantic cluster sizes, and greater than normal percentages of errors and category labels. On category fluency tasks, patients generate a greater proportion of words that are prototypical of their semantic class. To determine whether any of these supplementary measures of verbal fluency performance might be useful in revealing processes involved in the decline of semantic memory in AD, we studied 219 patients with AD and 115 elderly control participants longitudinally. Previously reported group differences between patients and controls were replicated, but changes in average cluster size, error rates, and prototypicality were not related to changes in overall severity of dementia and test-retest stability was only modest. The change in the percentage of labels generated on the Supermarket task was related to changes in dementia severity, but test-retest stability on this measure was quite low. All of these process measures appear to reflect only the current status of the patient's attention to the task and access to semantic knowledge, but they do not forecast future performance. The numbers of switching responses on the fluency tasks were sensitive to differences between clinically deteriorated and clinically stable patients and showed fairly high test-retest stability. However, the number of switching responses is so highly correlated with the number of correct words that it contributes little to the understanding of the processes involved in the progressive decline in performance on fluency tasks by patients with AD.