Orienting in Schizophrenia: Habituation to Auditory Stimuli of Constant and Varying Intensity in Patients High and Low in Skin Conductance Responsivity

Groups of schizophrenics and normal controls were exposed to different series of tones of constant (80dB) and variable intensity (60, 80, and 100 dB). Measurements included bilateral skin conductance, finger pulse volume, and heart rate. Both groups were split on the common median in skin conductance response to constant intensity tones to form matched patient and control groups of low and high responsivity. The low and high responsive schizophrenic groups were more clearly separated than the two control groups in rate of spontaneous skin conductance fluctuations, skin conductance magnitudes, and skin conductance levels, primarily because of generalized hyperactivity in high responsive patients. This pattern was clearest for the most intense tone and left hand recordings. High responsive schizophrenics also showed larger response amplitudes, shorter rise and recovery times, and a smaller ratio of elicited to spontaneous responses, than high responsive controls. Finger pulse volume responses recorded from the left hand were smaller in the patient groups, whereas patients and controls did not differ in right hand recordings. High skin conductance responsive subjects showed more heart rate deceleration than low responsive subjects, and schizophrenics had more decelerative responses than controls.     

Psychopathy and Physiological Responses to Threat of an Aversive Stimulus

Physiological activity was monitored while 64 prison inmates awaited delivery of a 120dB tone during a 12-sec “count-down” procedure. The inmates were divided into four groups on the basis of global ratings of psychopathy (interrater reliability = .86) and scores on the Socialization (So) scale. Twelve inmates in the group considered to be most psychopathic (high ratings of psychopathy and low So scores) showed larger increases in heart rate and smaller increases in electrodermal activity in anticipation of the tone than did 20 inmates in the group considered to be least psychopathic (low ratings of psychopathy and high So scores). These findings were consistent with those of several previous studies, and were interpreted as a reflection of an association between psychopathy and the operation of efficient mechanisms for coping with threat.     

Psychophysiology of sociopathy: electrocortical measures.

The CNV, visual AEP and resting EEG were analyzed in sociopaths and controls matched for age and sex. Twenty-seven male sociopaths were selected by psychiatric interview and special rating scale, restricted to Shipley-Hartford IQs of 115-145 and separated into young (x = 20.5 yr) and older (x = 35.3 yr) age groups. Subjects participated in forewarned reaction-time tasks in which the imperative stimulus was either an innocuous or noxious tone that the subject escaped by pressing a response key. Sociopaths and controls did not differ in reaction time, vertex and occipital AEP amplitude or latency, and power spectral density of the EEG. Contrary to previous findings, there also were no significant differences between sociopaths and controls in overall CNV amplitude or topography. However, while most controls showed increased CNV amplitude in the noxious tone condition as compared to the innocuous tone condition, older sociopaths showed no change, or decreased amplitudes.     

Paranoid-nonparanoid differences--psychophysiological parallels.

It was predicted that the psychological differences between paranoids and nonparanoids would be parallelled by differences in psychophysiological responses to stimuli varying along both informational and motivational dimensions. Skin conductance and heart rate responses to stimuli in a guessing task were measured in a group of paranoid patients and compared with those from non-paranoid and non-patient controls. A group of nonschizophrenic patients on phenothiazine medication served as drug-matched controls. Skin conductance level, response frequency and amplitude data are reported; heart rate response changes were examined by means of times series analysis and reported as first and second deceleration and first and second acceleration components. It was predicted that paranoid patients would show a greater increase in skin conductance measures with cognitive demand, and an increase in acceleratory components of the heart rate to increases in motivational variables. The normal pattern of greater electrodermal responding to the negative stimuli than the positive, and greater heart rate acceleration to the positive stimuli but not the negative (Fowles, 1980) was predicted to be reversed in schizophrenic patients, and possibly more marked in paranoids. Cognitive manipulations showed the predicted increase in electrodermal and heart rate responding in normal controls. The paranoid subjects showed a similar increase as a function of task demands, but there was no significant difference between the other groups. Motivational manipulations produced increased skin conductance responding and increases in heart rate acceleration components in normal controls, this was not parallelled in the patient groups. All subject groups failed to show greater electrodermal activity to negative than to positive stimuli. Normal controls showed significant heart rate acceleration to positive as compared to negative stimuli, this pattern was reversed in paranoid patients.     

Effects of Arousal on Habituation of the Electrodermal Orienting Reflex

The effect of level of arousal upon rate of habituation of the electrodermal orienting reflex (OR) was studied by having 20 tone stimuli presented while subjects were either standing or seated. The standing condition was characterized by both a higher heart rate (HR) and a greater frequency of spontaneous skin resistance responses (SRRs). Compared to standing subjects, subjects under the seated condition demonstrated more rapid habituation of the OR as indicated both by a greater decrement in SRR frequency from the first to the last block of trials and by a greater proportion of subjects who failed to respond to any of the last 10 trials. The rate of spontaneous SRRs appeared to parallel these differences in habituation of evoked responses. There were no differences between groups in skin conductance level (SCL), or in either amplitude or frequency of the evoked electrodermal response over the first few stimulus presentations. The results were interpreted as supporting the conclusion that heightened arousal level retards habituation of the OR.     

Individual Differences in Fear and Autonomic Reactions to Affective Stimulation

Klorman et al. (1975) found that mutilation-fearful persons reacted with heart rate speeding to mutilation slides and to neutral stimuli. The within-subject design of that study suggested that these paradoxical reactions to neutral slides may have been due to subjects' anticipation of phobic materials. In the present work, 84 female subjects, categorized by a standardized questionnaire as high or low in fear of mutilation, viewed one of three types of slides: 1) mutilated bodies; 2) persons and objects in incongruous or humorous poses; or 3) standard photographs of persons, objects, and landscapes. Mutilation materials evoked cardiac acceleration and high subjective tension in fearful subjects vs bradycardia and moderate tension in low-fear subjects. Neutral and incongruous slides prompted similar reactions from both fear groups: heart rate deceleration and low tension. Low-fear subjects shown mutilation slides tended to exceed the groups receiving nonaversive stimulation in magnitude of cardiac deceleration. Extensive analyses of respiratory activity showed that these differential heart rate reactions were not attributable to breathing. Mutilation stimuli evoked greater skin conductance responses than nonaversive slides, but there were no electrodermal differences as a function of fear relevance. The lawful relationship uncovered in the present research between cardiac reactions and individual differences in fear supports our suggestion that anticipation may have played a role in our earlier work.     

Changes in autonomic cardiovascular control in mid-pregnancy.

Spectral analysis of heart rate variability was used to study autonomic nervous control in mid-pregnancy. Fifty women (age 22-36 years) with singleton pregnancies (mean duration of gestation 27.7 weeks) and 39 non-pregnant female controls (age 21-39 years) were studied using controlled breathing and orthostatic tests. During spontaneous breathing the overall heart rate variability was lower in pregnant subjects indicating a decreased parasympathetic tone at rest. The decreased parasympathetic tone probably counts for the increased heart rate in pregnancy. The parasympathetic efferent capacity of autonomic cardiac control was found to be similar in pregnant and non-pregnant subjects, as no difference was seen during controlled breathing in periodic heart rate variability between the groups. Standing up caused a similar change in low frequency and mid-frequency bands in both groups, but high frequency heart rate variability increased in pregnant subjects and decreased in the controls indicating an increased sympathetic tone at rest in mid-pregnancy.     

Heart Rate, Contingent Negative Variation, and Evoked Potentials during Anticipation of Affective Stimulation

Thirteen subjects low in fear of mutilation and 11 subjects high in this fear were exposed to repeated presentations of a 6-sec tone followed by slides depicting a mutilated body or a 6-sec tone of a different frequency paired with a slide of a neutral scene. For both groups, the N140 component of the evoked potential was larger following the signal for gruesome slides. Slow EEG activity displayed two negative waves. Notably, the late CNV wave was present even though a motor response was not required at the end of the foreperiod. Overall, high-fear subjects' early waves tended to be larger preceding neutral scenes than gruesome slides, whereas low-fear subjects showed a trend in the opposite direction. Similar but largely nonsignificant trends were present for the late wave. Heart rate reactions of both groups in the foreperiod included an early deceleration, acceleration, and a late deceleration. Among high-fear subjects both the acceleratory and late deceleratory limbs were greater preceding mutilation than neutral slides. In contrast, low-fear subjects' reactions lacked the acceleratory reaction and did not vary as a function of type of warning signal. These results, therefore, indicate differential autonomic patterns of anticipation of affective stimulation as a function of individual differences in fear.     

Electromyographic and affective responses of episodic tension-type headache patients and headache-free controls during stressful task performance

Thirty-four subjects meeting diagnostic criteria for episodic tension-type headache and 42 who rarely experienced headaches participated in two laboratory sessions in which cephalic electromyographic (EMG) activity, electrodermal activity, heart rate, and finger temperature were recorded. Subjects performed relaxation, choice reaction time, psychomotor tracking, voluntary muscle contraction, and cold pressor tasks. Headache subjects showed significantly greater EMG activity than controls during baseline and stressful task performance. During relaxation, both groups reduced EMG activity from baseline levels, and there was no significant difference in EMG level between the groups during relaxation. Headache subjects reported higher levels of subjective anxiety, depression, anger, and stress than controls. Headache subjects also reported higher levels of pain than controls, and headache subjects reported greater pain during stressful task performance relative to baseline and recovery periods.This research was supported by NIH Grant R01-NS-25114.     

Responsiveness patterns and handedness differences in bilateral electrodermal asymmetry.

The aim of the present study was to examine the relationship between subjects' handedness and electrodermal asymmetry when subjects were divided according to their electrodermal Responsiveness Patterns, obtained during a stimulus-free period. Skin conductance was bilaterally recorded in a sample of 48 subjects (24 dextrals and 24 sinistrals) during the performance of two tasks (watching a film and listening to neutral tones). Subjects were divided into four groups of 12 subjects each (dextral right-hand responders, dextral left-hand responders, sinistral right-hand responders and sinistral left-hand responders). No differences were found between dextral and sinistral subjects. Orientation of electrodermal asymmetry in each Responsiveness Patterns remained constant throughout the two conditions: right-hand responders showed higher electrodermal activity on their right hand, while left-hand responders showed higher electrodermal activity on their left hand. In addition, left-hand responders showed a slower habituation rate on their left hand than on their right hand, whereas right-hand responders showed no significant differences between hands.     

Hypnotic susceptibility: a lateral predisposition and altered cerebral asymmetry under hypnosis

Psychophysiological and behavioural evidence is reported of altered cerebral asymmetry under hypnosis in favour of the right hemisphere. This occurred in Susceptible as distinct from Unsusceptible subjects. Measures included bilateral electrodermal responses to tones and bimanual processing times for sorting letters and numbers with eyes closed. Subjects listened to a tape recording of a procedure for inducing relaxation under hypnosis. Susceptible subjects, unlike Unsusceptibles, showed lateral asymmetries in baseline conditions in favour of the left hemisphere. Electrodermal responses were larger on the left than the right hand and haptic processing times were faster with the right than the left hand. Under hypnosis there was a reduction in electrodermal orienting responses coupled with faster habituation and a reversal in lateral asymmetries. Haptic processing revealed a slowing in right hand processing times whereas left hand times were reduced as was the case with bilateral processing times in both Unsusceptible subjects and controls who experienced no hypnosis. Unlike earlier reports left hemisphere dynamic processes were fundamental to the induction of hypnosis. A neuropsychological model is proposed whereby susceptibility is associated both with a left bias prior to hypnosis and left hemisphere inhibition under hypnosis. Unsusceptibles retain a right hemisphere orientation without undergoing left hemisphere inhibition. Thus hypnosis involves an inhibition of left-sided processes which permits the ascendancy of the right hemisphere through the attenuation of left hemisphere control.     

Cardiovascular and Electrodermal Response Patterns in Heart Rate Reactive Individuals During Psychological Stress

The goal of this research was to examine the cardiovascular and electrodermal response patterns of heart rate reactive and nonreactive individuals to psychological stress. Sixty males were tested while resting, listening to tones, identifying tone patterns, and performing mental arithmetic. Dependent variables were blood pressure, heart rate (HR), and skin conductance responses. Based on the change in HR from baseline to the first minute of mental arithmetic, two extreme reactivity groups of 15 subjects each were formed. Results indicated that HR reactive subjects had higher systolic blood pressure and HR than nonreactives. Reactives showed greater HR lability during all the tasks and a phasic acceleration to tones, while nonreactives showed a deceleration. Finally, comparisons of skin conductance responses indicated that subjects who were nonreactive when measuring HR were more reactive when measuring skin conductance. The HR reactivity seen in these subjects has been linked to predisposition to psychosomatic illness, and the current findings are discussed in that light.     

Startle potentiation during anticipation of a noxious stimulus: Active versus passive response sets

The startle reflex response increases during aversive stimulus processing. This study examined whether differing response sets affected startle potentiation during anticipation of an aversive event. Two groups received a noxious noise blast following a 6-s warning cue. Subjects in the active group could press a switch to stop the noise; yoked passive subjects received the same noises with no control. Subjects in a yoked control group heard a soft tone following cue offset. Acoustic startle probes were presented during some of the warning periods and during some of the intertrial intervals. The major finding was that the active and passive groups did not differ in startle potentiation. In comparison with controls, startle reactions for both groups were larger and faster during the warning cue than between trials. The results suggest that the startle reflex indexes defensive response mobilization independently of specific task demands.     

Do Instructions Modify Effects of Beta-adrenoceptor Blockade on Anxiety?

To study the interaction between physiological and cognitive factors in anxiety, 44 subjects with public speaking anxiety were allocated to four different groups. Two groups received either beta-adrenoceptor blockade (100 mg of atenolol) or placebo orthogonally crossed with an instruction that heart rate would decrease or an instruction that did not mention cardiovascular effects. During the delivery of a speech, measures of heart rate, systolic and diastolic blood pressures, and self-reported anxiety were obtained. All variables increased during an anticipation period before speech, and heart rate, systolic blood pressure, and self-reported anxiety increased further during speech. Regardless of instructions, atenolol decreased heart rate and systolic blood pressure during both anticipation and speech, whereas no differences were found in self-reported anxiety. This lack of a relationship was seen in spite of the correctly perceived heart rate reduction in the atenolol-treated group receiving an instruction that heart rate would decrease. Cardiac aware subjects, according to the Autonomic Perception Questionnaire, showed higher levels of heart rate and self-reported anxiety at rest than did cardiac unaware subjects. During speech, even though heart rate was similar in atenolol treated groups, self-reported anxiety was higher in cardiac aware than in cardiac unaware subjects. The lack of a relationship between heart rate and self-reported anxiety is discussed in terms of primary and secondary emotions. It is suggested that the perception of external rather than internal cues determines situationally elicited anxiety.     

Electrodermal Nonresponding Among College Undergraduates: Temporal Stability, Situational Specificity, and Relationship To Heart Rate Change

Based on a large screening project, 24 electrodermal nonresponders to nonsignal tones were chosen from an undergraduate population and compared on multiple electrodermal, heart rate, and personality measures to an equal number of randomly selected control subjects. Questions addressed in this study included the reliability of the nonresponder category with repeated testing, its stability across situations, its concurrent relationship with other psychophysiological measures, and its ability to predict scores on more standardized measures of individual differences. It was determined that nonresponders continued to produce smaller specific skin conductance responses (SCRs) during a second testing session two weeks after the initial screening, and these differences remained when subjects were tested under signal conditions. However, 50% of the initial nonresponders did produce SCRs by the completion of all testing. Nonresponders and controls differed on other electrodermal measures as well, with nonresponders producing fewer spontaneous fluctuations under all conditions and lower skin conductance levels during initial screening and under signal conditions. Nonresponders and control subjects also differed in heart rate response during the signal procedure. Control subjects produced the anticipated cardiac deceleration, whereas nonresponders produced a pronounced heart rate increase. The two groups did not differ on measured personality characteristics, but when nonresponders were divided into subgroups based on consistency of response pattern, several differences did emerge.     

Sex differences and the asymmetry of specific and non-specific electrodermal responses

Phasic electrodermal conductance responses were bilaterally recorded from 30 subjects (15 males and 15 females). After a 5-min adaptation period subjects were presented with two series of ten 80-dB tones each, with a 4-min rest period between the two series. Data from sinistrals, ambidextrous, and from subjects with familial sinistrality were excluded from statistical analysis. Males displayed more asymmetry between hands both in their non-specific and specific responses, with larger skin conductance responses on the left hand. Females showed a less marked asymmetry, with larger skin conductance responses on the right hand. Similar results were found in skin conductance levels. It was concluded that sex differences are an important variable in the study of electrodermal asymmetry.     

Effects of stimulus intensity, risetime, and duration on autonomic and behavioral responding: implications for the differentiation of orienting, startle, and defense responses.

The effects of stimulus intensity, duration, and risetime on the autonomic and behavioral components of orienting, startle, and defense responses were investigated. Six groups of 10 students were presented with 15 white noise stimuli at either 60 or 100 dB, with controlled risetimes of either 5 or 200 ms, and at stimulus durations of 1 or 5 s (1 s only in the case of the 60-dB groups). A dishabituation stimulus consisting of a 1000 Hz tone was also presented. Measures consisted of skin conductance and heart rate, together with ratings of facial expressions and upper torso movement obtained using video recording. Increased intensity resulted in greater amplitudes and frequencies of electrodermal and behavioral responses, and a change from cardiac deceleration to acceleration. Faster risetimes elicited larger electrodermal responses, greater frequencies of eye-blinks, head and body movements, and larger cardiac accelerations. The effects of duration for the 100-dB stimuli were less clear-cut. Overall, the results are discussed in relation to the differentiation of orienting, startle, and defense responses.     

Psychopathy and Physiological Activity During Anticipation of an Aversive Stimulus in a Distraction Paradigm

Two investigators independently rated 51 white, male prison inmates on a 7-point psychopathy scale (interrater reliability = .89). The combined ratings were used to divide the inmates into low (1), medium (M). and high (H) psychopathy groups of 17 subjects each. Following a sample trial, each inmate was given two trials in which he could choose how to spend his time during a 5–6 min wait for an aversive stimulus (120dB tone). Three choices were available: 1) continuous white noise, 2) a recording of a nightclub comedian, or 3) a continuous tone that changed in frequency 10 sec before delivery of the aversive stimulus. The aversive stimulus could be avoided on one trial but not on I he other (the order was counterbalanced). When the aversive stimulus was unavoidable (Trial UA), 46 (90.2%) of the inmates spent all or most of their time listening to the comedian, i.e., they adopted a “nonvigilant” strategy, while 38 (74.5%) adopted this strategy when the aversive stimulus was avoidable (Trial A). There were no group differences in the type of strategy used on either trial, or in the physiological responses given by the nonvigilant subjects on Trial UA. Group H tended to give smaller electrodermal responses and a larger increase in HR in anticipation of the sample tone than did Group L, a pattern that is consistent with previous research using classical conditioning or “count down” procedures. On Trial A the nonvigilant subjects in Group H showed a significantly smaller increase in nonspecific skin conductance activity than did Group L. It is suggested that making use of distraction when an aversive stimulus is avoidable results in less conflict and heightened emotional arousal in psychopaths than in other inmates. Some speculations on how psychopaths cope with threat are offered.     

Effects of Electrodermal Lability and Stimulus Significance on Electrodermal Response Amplitude to Stimulus Change

The effects of electrodermal lability and stimulus significance on the amplitude of the skin conductance response (SCR) component of the orienting response (OR) to stimulus change were examined. Subjects were pre-selected in terms of the frequency of nonspecific responses (NSRs) displayed during a period of no stimulation. In Experiment 1 (N = 56), high and low NSR male subjects received 12 presentations of a 5-sec, 1000 Hz tone followed by a test trial on which tone frequency was 500 Hz. Half of the subjects in each NSR group were required to perform a reaction time (RT) response to stimulus offset. Although high NSR groups and RT groups displayed larger test-trial responses than low NSR and no-RT groups respectively, stimulus change alone was sufficient to produce an increase in SCR amplitude. In Experiment 2 (N = 40), high and low NSR male subjects received 12 visually-presented female names, and on trial 13, half the subjects in each NSR group received their own name, while the other half received a neutral male name. High NSR groups and own-name groups displayed larger test-trial responses than low NSR groups and neutral-name groups respectively. However, stimulus change alone was sufficient to produce an increase in SCR amplitude in the high NSR group. The results are interpreted as indicating that stimulus change alone is sufficient to produce an increase in OR amplitude, and that the relationship between stimulus change and stimulus significance is additive rather than multiplicative.     

The contingent negative variation (CNV) to fear-related stimuli in acquisition and extinction

Contingent Negative Variation (CNV) in anticipation of phobic and neutral slide material was recorded in Acquisition of a learned association between tone pitch and slide type, and in Extinction (following removal of slide presentation). In phobic volunteers, no clear CNV differentiation between 'phobic' and control condition was apparent in either Acquisition or Extinction. For Control subjects, a different pattern entirely has been demonstrated, with anticipation of the neutral condition giving rise to a larger CNV than anticipation of the 'phobic' condition (in Acquisition). In addition, Extinction led to a reversal of this CNV amplitude relationship, with the tone previously associated with the phobic slide producing a DC-shift which was larger than that following the tone previously paired with the neutral slide. The results are compatible with a dynamic model of CNV generation according to which CNV amplitude is positively related to an expectancy for reward or non-punishment but inversely related to an expectancy for punishment or non-reward.