Michael E. Dawson

The psychological significance of human startle eyeblink modification: a review.

The human startle eyeblink reflex is reliably modified by both cognitive and emotional processes. This review provides a comprehensive survey of the current literature on human startle modification and its psychological significance. Issues raised for short lead interval startle inhibition include its interpretation as a measure of protection of processing, sensorimotor gating and early attentional processing. For long lead interval effects, interpretations related to attentional and emotional processing are discussed. Also reviewed are clinical applications to information processing dysfunctions in the schizophrenia spectrum disorders, and to emotional processing disorders. Finally, an integrative summary that incorporates most of the cognitive findings is presented and directions for future research are identified regarding both cognitive and emotional modification of startle.

Modification of the acoustic startle-reflex eyeblink: A tool for investigating early and late attentional processes

The present experiment examined the sensitivity of short and long lead interval startle eyeblink modification to attentional processing. Eighteen college student subjects were presented with a series of intermixed high and low pitched tones and instructed to attend to tones of one pitch and to ignore tones of the other pitch. The majority of the attended and ignored tones served as prepulses for an eyeblink-eliciting burst of white noise presented at lead intervals of 60, 120, 240 and 2000 ms following prepulse onset. Results indicate that both attended and ignored prepulses produce significant startle eyeblink modification: significant blink inhibition at the 60, 120 and 240 ms short lead intervals, and blink facilitation at the 2000 ms long lead interval. In addition, compared with the ignored prepulse, the attended prepulse produced significantly greater blink inhibition at the 120 ms lead interval as well as significantly greater blink facilitation at the 2000 ms lead interval. These results suggest that both short and long lead interval startle eyeblink modification measures may be useful tools for future investigations of the early and later stages of attentional processing.

Attention and schizophrenia: Impaired modulation of the startle reflex.

The startle reflex (SR) elicited by abrupt stimuli can be modified by attention to nonstartling stimuli that shortly precede the startle-eliciting stimulus. The present study of 15 recent-onset, relatively asymptomatic schizophrenic outpatients and 14 demographically matched normal control subjects demonstrated that attentional modulation of SR is impaired in schizophrenic patients. Specifically, the control group exhibited greater startle eye-blink modification following to-be-attended prestimuli than following to-be-ignored prestimuli, whereas the patients failed to show the attentional modulation effect. These results suggest traitlike attentional deficits in schizophrenia because the patients were relatively asymptomatic. The measurement of attentional modulation of SR may provide a nonverbal, reflexive, state-independent marker of the vulnerability to schizophrenia.

Information-processing abnormalities as neuropsychological vulnerability indicators for schizophrenia

Studies of schizophrenic patients in psychotic and clinically remitted states and of biological relatives indicate that subtle anomalies in information processing may be critical components of neuropsychological vulnerability to schizophrenia. We describe a conception of possible abnormalities and several recent strategies to differentiate these possibilities. Within Continuous Performance Test conditions, varying the perceptual load vs. the active, working memory load yields a distinction between a stable vulnerability factor across clinical states and a potential mediating vulnerability factor. Specialized backward masking paradigms offer ways to separate two initial sensory‐perceptual processes from attentional shifting processes. Top‐down attentional influences on sensorimotor gating allow examination of the role of central executive processes in modulating early sensory processes. Initial results are discussed.

The vulnerability/stress model of schizophrenic relapse: a longitudinal study

A tentative model for conceptualizing the interplay of vulnerability factors, stressors, and protective factors in the course of schizophrenia is discussed. A study of the initial years after a first schizophrenic episode is testing the predictive role of key factors. During an initial 1‐year period of depot antipsychotic medication, independent life events and expressed emotion were found to predict the likelihood of psychotic relapse. Initial analyses indicate that independent life events play less of a role in relapse prediction during a medication‐free period. These results suggest that maintenance antipsychotic medication raises the threshold for return of psychotic symptoms, such that relapses are less likely unless major environmental stressors occur. A low expressed emotion environment may be a protective factor.

Association of Poor Childhood Fear Conditioning and Adult Crime

OBJECTIVE Amygdala dysfunction is theorized to give rise to poor fear conditioning, which in turn predisposes to crime, but it is not known whether poor conditioning precedes criminal offending. This study prospectively assessed whether poor fear conditioning early in life predisposes to adult crime in a large cohort. METHOD Electrodermal fear conditioning was assessed in a cohort of 1,795 children at age 3, and registration for criminal offending was ascertained at age 23. In a case-control design, 137 cohort members with a criminal record were matched on gender, ethnicity, and social adversity with 274 noncriminal comparison members. Statistical analyses compared childhood fear conditioning for the two groups. RESULTS Criminal offenders showed significantly reduced electrodermal fear conditioning at age 3 compared to matched comparison subjects. CONCLUSIONS Poor fear conditioning at age 3 predisposes to crime at age 23. Poor fear conditioning early in life implicates amygdala and ventral prefrontal cortex dysfunction and a lack of fear of socializing punishments in children who grow up to become criminals. These findings are consistent with a neurodevelopmental contribution to crime causation.

On the clinical and cognitive meaning of impaired sensorimotor gating in schizophrenia.

Schizophrenia patients have been shown to have a defective sensorimotor gating process as indexed by impaired prepulse inhibition of the startle eyeblink reflex. Moreover, we have previously reported that schizophrenia patients have dysfunctional attentional modulation of prepulse inhibition. The present experiment combined our previous sample of 14 schizophrenia outpatients and 12 demographically matched control subjects with a new sample of 10 outpatients and 6 control subjects. All participants performed a tone-length judgement task that involved attending to one pitch of tone (the attended prepulse) and ignoring another pitch of tone (the ignored prepulse). During this task the acoustic startle eyeblink reflex was electromyographically recorded from the orbicularis oculi muscle. The results replicated the finding of impaired attentional modulation of prepulse inhibition in the new sample of schizophrenia outpatients compared to demographically matched control subjects. Specifically, the new control group exhibited greater startle modification during the attended prepulse, whereas the new patient group failed to show this differential effect. In addition, impaired prepulse inhibition following the attended prepulse was significantly correlated with heightened delusions, conceptual disorganization, and suspiciousness as measured with the expanded Brief Psychiatric Rating Scale. These correlations were significant with prepulse inhibition to the attended prepulse but not with prepulse inhibition to the ignored prepulse. Impaired prepulse inhibition was not correlated with negative symptoms. All in all, the results support the hypothesis that impaired attentional modulation of startle prepulse inhibition reflects basic neurocognitive processes related to thought disorder in schizophrenia.

Modification of the Startle Reflex in a Community Sample: Do One or Two Dimensions of Psychopathy Underlie Emotional Processing?

Recent research on psychopathy has begun to explore two dimensions that possibly underlie psychopathy–one related more to emotional and interpersonal traits, and another related more to antisocial behaviors. A community sample of adults was assessed for psychopathy using Hares (1991) Psychopathy Checklist-Revised (PCL-R). Eyeblinks elicited by startle probes were recorded while participants viewed pictures of emotionally-laden stimuli. Consistent with previous research, participants scoring high on PCL-R Factor 2 (“antisocial”) showed no affective modification of startle if they also scored high on PCL-R Factor 1 (“emotional detachment”). When the factor scores were analyzed together as continuous variables in a regression analysis, however, affective modification of startle was negatively related to Factor 1 but positively related to Factor 2. The results thus provide further support for a two-factor model of psychopathy.Emotion

Optimal Arousal Identification and Classification for Affective Computing Using Physiological Signals: Virtual Reality Stroop Task

A closed-loop system that offers real-time assessment and manipulation of a users affective and cognitive states is very useful in developing adaptive environments which respond in a rational and strategic fashion to real-time changes in user affect, cognition, and motivation. The goal is to progress the user from suboptimal cognitive and affective states toward an optimal state that enhances user performance. In order to achieve this, there is need for assessment of both 1) the optimal affective/cognitive state and 2) the observed user state. This paper presents approaches for assessing these two states. Arousal, an important dimension of affect, is focused upon because of its close relation to a users cognitive performance, as indicated by the Yerkes-Dodson Law. Herein, we make use of a Virtual Reality Stroop Task (VRST) from the Virtual Reality Cognitive Performance Assessment Test (VRCPAT) to identify the optimal arousal level that can serve as the affective/cognitive state goal. Three stimuli presentations (with distinct arousal levels) in the VRST are selected. We demonstrate that when reaction time is used as the performance measure, one of the three stimuli presentations can elicit the optimal level of arousal for most subjects. Further, results suggest that high classification rates can be achieved when a support vector machine is used to classify the psychophysiological responses (skin conductance level, respiration, ECG, and EEG) in these three stimuli presentations into three arousal levels. This research reflects progress toward the implementation of a closed-loop affective computing system.

Reduced electrodermal fear conditioning from ages 3 to 8 years is associated with aggressive behavior at age 8 years.

BACKGROUND Poor fear conditioning characterizes adult psychopathy and criminality, but it is not known whether it is related to aggressive/antisocial behavior in early childhood. METHODS Using a differential, partial reinforcement conditioning paradigm, electrodermal activity was recorded from 200 male and female children at ages 3, 4, 5, 6, and 8 years. Antisocial/aggressive and hyperactive-inattentive measures were collected at age 8. RESULTS Poor electrodermal fear conditioning from ages 3 to 8 years was associated with aggressive behavior at age 8 in both males and females. CONCLUSIONS Results indicate that the relationship between poor fear conditioning and aggression occurs early in childhood. Enhanced electrodermal fear conditioning may protect children against future aggressive/violent behavior. Abnormal amygdala functioning, as indirectly assessed by fear conditioning, may be one of the factors influencing the development of childhood aggression.