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R F Simons

Publications and source records attributed to R F Simons.

32 records · Page 2Linked to original sources
PubMed1985

Event-related potentials elicited by automatic targets: a dual-task analysis.

The role of limited capacity processes in the detection of automatic targets was investigated in a dual-task paradigm using both behavioral and event-related brain potential (ERP) measures. An automatic detection task was paired with another concurrent discrimination while the relative importance of each task was systematically varied. The resulting performance operating characteristic (POC) showed that both the speed and accuracy of automatic detection responses were affected by the allocation of attention. Reductions in the accuracy of each task were accompanied by reductions in the amplitude of a late-positive component of the ERP (P300). In addition, the latency of the P300 component elicited by automatic targets was increased in dual-task conditions. A comparison of behavioral and ERP measures suggested the involvement of two separate limited-capacity processes in automatic detection: one concerned with the formation of an episodic representation of target occurrence and the other with the execution of rapid motor responses.

Attention↗
PubMed1981

Electrodermal and cardiac orienting in psychometrically defined high-risk subjects.

The vast majority of research programs investigating subjects at high risk for psychopathology have relied on genetic criteria for subject selection. Recent reports, however, have begun to suggest alternative definitions and sets of criteria for the selection of high-risk subjects. One such alternative is a psychometric definition of risk--the selection of subjects on the basis of psychological test data. The present experiment used this strategy to study orienting and habituation to simple auditory stimuli in groups of young adult subjects reporting either physical anhedonia or perceptual aberrations. The study provided support for the hypothesized continuity between anhedonic subjects and the autonomically hyporesponsive group of patients frequently described in the literature on schizophrenia. Results are discussed in light of recent appeals to identify biologically homogeneous subgroups of schizophrenic patients.

Adolescent↗
PubMed1976

Psychophysical judgment: electro-cortical and heart rate correlates of accuracy and uncertainty.

The relationship between perceptual accuracy and physiological response amplitude was investigated in an auditory pitch discrimination experiment. Confidence ratings were obtained from all subjects following each trial. The stimulus set consisted of three tones of different frequencies spaced in a manner to provide both easy and difficult discriminations. Heart rate, EEG and vertical eye movement were recorded throughout the experiment. The results of the experiment indicated that the largest evoked cardiac rate response was elicited by the stimulus which produced the fewest errors in judgment; larger auditory evoked potentials, particularly the late positive component (P300), were associated with the 'easy' stimulus; greater cortical negativity was associated with the difficult stimuli. Eye activity was found to covary with judgmental accuracy; cortical slow wave activity was particularly sensitive to the confidence, or 'uncertainty' parameter. A 'decision tree' model was hypothesized to describe the processing mechanism involved in solving the discrimination problem.

Acoustic Stimulation↗
PubMedDate not supplied

Anticipatory pleasure deficit in subjects reporting physical anhedonia: slow cortical evidence.

Slow cortical and heart rate responses were recorded from anhedonic and normal control subjects during a two-stimulus anticipation paradigm. Subjects were chosen for participation in the experiment based on their scores on the Physical Anhedonia Scale developed by Chapman, Chapman and Raulin (1976). During the procedure, auditory warning stimuli were delivered which informed subjects that a visual stimulus (color slide) would follow shortly and specified the category of the slide (neutral or high-interest) which was to be presented. Results of this investigation revealed that anhedonic subjects showed less differential physiological responsivity while anticipating high and low interest stimuli than did normal controls. This was most striking in the slow cortical response (CNV) which appears particularly sensitive to such motivational and/or attentional manipulations. The data are discussed with respect to emotion and psychopathology.

Adult↗
PubMedDate not supplied

The component structure of event-related slow potentials: task, ISI, and warning stimulus effects on the 'E' wave.

Two experiments were conducted to investigate the role of task variables and ISI length on the late component of the event-related slow potential (ERSP) recorded during various two-stimulus anticipation tasks. In the first experiment, a two-component ERSP was observed during short (1 sec) and long (4 sec) ISI conditions. The first component was generally Fz dominant and independent of task variables. The second component was generally Cz dominant and most prominent when an immediate motor response was required. A second experiment was successful in eliciting large second ERSP components even in the absence of response requirements. In this experiment, the topography of the second component was not exclusively Cz dominant; rather, it was task dependent, and achieved Fz dominance under delayed-response conditions. Heart rate, monitored concurrently with the EEG, also reflected the change in experimental conditions by the enhancement of a mid-ISI acceleratory component. The data are discussed with respect to a multiple-component model of slow potential activity during periods in which subjects anticipate significant events.

Adolescent↗