HABITUATION OF THE ORIENTING REFLEX IN BRAIN DAMAGED PATIENTS

Habituation and dishabituation of the heart rate, skin conductance, and alpha blocking components of the orienting reflex to an auditory stimulus were examined for brain-damaged and non-brain-damaged Ss. The non-brain-damaged group displayed the expected habituation for all of these response variables but the brain-damaged group displayed evidence of habituation only for the skin conductance measure. The brain-damaged group also displayed higher initial skin conductance response amplitudes and smaller initial alpha blocking responses to the auditory stimulus than did the non-brain-damaged group. The results are discussed in terms of their implications for mechanisms of habituation and for other psychological deficits in brain-damaged patients.     

Physiological Responses to Clicks during Zen, Yoga, and TM Meditation

Two studies have been widely quoted as indicating the differing states of consciousness in Zen vs Yoga meditation. A replication and extension were attempted. Very experienced Zen, Yoga, and TM meditators with average lengths of experience of 7.5 yrs, 5 yrs, and 7 yrs, respectively, and two groups of controls were presented with auditory clicks during meditation. EEG alpha suppression and skin conductance response both showed clear habituation which did not differ among groups, thus failing to replicate the earlier studies. The N100, P200, and P300 components of the EEG average evoked potential were also measured.     

Autonomic and EEG patterns distinguish transcending from other experiences during Transcendental Meditation practice.

This study compared EEG and autonomic patterns during transcending to "other" experiences during Transcendental Meditation (TM) practice. To correlate specific meditation experiences with physiological measures, the experimenter rang a bell three times during the TM session. Subjects categorized their experiences around each bell ring. Transcending, in comparison to "other" experiences during TM practice, was marked by: (1) significantly lower breath rates; (2) higher respiratory sinus arrhythmia amplitudes; (3) higher EEG alpha amplitude; and (4) higher alpha coherence. In addition, skin conductance responses to the experimenter-initiated bell rings were larger during transcending. These findings suggest that monitoring patterns of physiological variables may index dynamically changing inner experiences during meditation practice. This could allow a more precise investigation into the nature of meditation experiences and a more accurate comparison of meditation states with other eyes-closed conditions.     

Effects of expectancy on physiological responsivity in novice meditators

Forty non-meditators were randomly assigned to 4 experimental cells devised to control for order and expectation effects. The subjects (all female) were continuously monitored on 7 physiological measures during both meditation and rest. Each subject was her own control in an 'abab' experimental paradigm comparing meditation to rest. The subjects, meditating for the first time, showed marginally lower psychophysiological arousal during the meditation than rest condition for systolic blood pressure, heart rate, skin conductance level and digital skin temperature. Deliberately fostering positive expectations of meditation was associated with lower physiological arousal in terms of diastolic and systolic blood pressure, heart rate and skin conductance level.     

Psychophysiological response of ADHD children to reward and extinction

In this study, we examined heart rate and skin conductance levels of 18 children with attention-deficit hyperactivity disorder (ADHD) and 18 normal children as they performed a repetitive motor task during reward and extinction conditions. Fowles (1980, Psychophysiology, 17, 87–104; 1988, Psychophysiology, 25, 373–391) suggested that psychophysiological responsivity reflects activity in two of Gray's (1982, The neuropsychology of anxiety, Oxford University Press; 1987, The psychology of fear and stress, Cambridge University Press) motivational systems; heart rate reactivity during reward reflects activity in the behavioral activation system, and skin conductance reactivity during extinction reflects activity in the behavioral inhibition system. As predicted, control children showed increased heart rate when reward was present and increased skin conductance when reward was removed. Compared with controls, ADHD children failed to show increased skin conductance levels during extinction, suggesting a weak behavioral inhibition system. ADHD children also displayed faster heart rate habituation to reward.     

Autonomic, electroencephalographic, and myogenic activity accompanying startle and its habituation during mid-childhood

This study investigated (a) possible associations of the large individual variation in startle, with accompanying autonomic, central nervous system, and myogenic activities in a habituation paradigm; and (b) the patterns of habituation of these variables. Startle blinks to 40 noise bursts, heart rate, alpha activity, and orbicularis oculi electromyographic (EMG) activity preceding and following each startle response were measured in 40 normal 7–11-year-old boys. Statle amplitude and its habituation were independent of association with either initial values or successive changes in the autonomic, alpha, and EMG activities; whereas startle habituated, pre-and poststartle myogenic, alpha, and cardiac activities failed to habituate. Tonic cardiac activity was facilitated, suggesting sensitization of state, as proposed in the dual-process theory of habituation.     

Anxiety and the Habituation of the Skin Conductance Response

The effect of threat of shock on the habituation of the skin conductance response (SCR) to a series of auditory stimuli was assessed. Skin resistance and heart rate were recorded during the presentation of 20, 1 sec, 1000 Hz tones in a control session and in a session at the end of which subjects were led to expect a painful electric shock. The effects of the threat of shock consisted of recovery of the SCR and an increase in skin conductance level and heart rate. They were restricted to the period during which subjects believed the shock to be imminent. Two possible reasons for the SCR recovery were offered, one in terms of Lader and Mathews' (1968) ‘maximal habituation’ hypothesis and a second in terms of a change in the stimulus complex.     

HEART RATE, SKIN CONDUCTANCE, AND INTENSITY RATINGS DURING EXPERIMENTALLY INDUCED ANXIETY: HABITUATION WITHIN AND AMONG DAYS

Twenty Ss were divided into two groups according to whether they received as a noxious stimulus in a count-up a mild shock or a punishing sound. Trials were varied over as well as within days. Among the findings: (1) There was considerable evidence of response fractionation among and within measures of heart rate, skin conductance, and rated stimulus intensity. (2) Trials over days exhibited an incubation effect for shock in the skin conductance data, a displacement of maximum heart rate reactivity toward the beginning of the time dimension, and a greater degree of habituation of the rated intensity of the shock stimulus than of the sound stimulus. It was concluded that habituation and incubation reflect cognitive processes, that the forward displacement of heart rate is the result of a centrally mediated inhibitory process, and that the gradient of such inhibition is steeper than the gradient of anxiety.     

Amplitude and Habituation of the Orienting Reflex as a Function of Stimulus Intensity

Two within-S experiments involving 20 Ss each and one between-S experiment employing 100 Ss were performed to examine effects of stimulus intensity on orienting response amplitude and habituation. Five intensities of a 1000 Hz tone were presented, ranging from 0 to 40 dB in Experiment I and from 0 to 80 dB in Experiments II and III. Response measures were skin conductance response (SCR) and heart rate (HR). Skin conductance response amplitude increased monotonically with stimulus intensity while HR deceleration was a generally decreasing function which tended to decrease, increase, and finally decrease again as intensity increased. Not only was deceleration greatest at 0 dB but it was more resistant to habituation. Several intensities of test stimulation were presented after habituating stimuli in the between-S experiment. Skin conductance response to test stimuli was facilitated by habituation at 0 dB and depressed by habituation at 80 dB. The results suggest a direct relationship between stimulus intensity and development of habituation.     

HGM1: a research-oriented portable heart rate and galvanic skin response monitor.

A convenient portable recording device, HGM1, which allows digital field recording of skin conductance and heart rate data with laboratory levels of precision, is described. Examples of individual data are provided from a study of orienting response habituation, and from students participating in a study of examination anxiety, recorded while they sat scheduled class examinations. These illustrate the potential value of the device in field studies.     

RATE OF HABITUATION AND THE LAW OF INITIAL VALUES

The galvanic skin response (GSR) data of two experiments were analyzed in an attempt to determine the effects of tonic shifts in baseline conductance on apparent rate of habituation. The results of the first experiment indicated that rate of habituation is exaggerated when response measures which are not base-independent are employed. The positive correlation found between habituation slope and an index of base-level change in conductance was significantly reduced when autonomic lability scores (ALSs) were used. Thus, base-corrected responses produced less steep habituation functions. The second experiment demonstrated that a tonic increase in conductance occurs to an intense auditory stimulus and that rate of habituation is consequently over-estimated in comparison to that associated with repeated presentation of a mild stimulus.     

The Relationship Between Cardiovascular Responses in the Laboratory and in the Field

The psychophysiological responses to laboratory stressors are often examined because it is believed that such responses relate to responsiveness in real life situations. This belief has seldom been tested. The changes in heart rate, pulse transit time, and respiration rate produced by a variety of laboratory tasks (active and passive coping and physical exercise) were related to ambulatory measures of heart rate in 32 young men. The field measures were the difference in heart rate between the waking day and when asleep, and estimates of the variability of heart rate during the day, derived from time series analyses. Average changes in heart rate and pulse transit time during specific tasks did not relate consistently to heart rate in the field. However, an active coping index, derived from the ratio of the peak heart rate during an active coping task to the peak during physical exercise related to all the field measures of heart rate responsiveness. This index, which may relate to measures of additional heart rate and heightened sympathetic response to stress, also correlated positively with Trait Anxiety and elevated basal sympathetic arousal, as measured by skin conductance level. Measures of the cardiovascular response to a passive coping task, the cold pressor, and exercise did not relate to heart rate responses in the field. The findings suggest that heightened cardiac responsiveness in real life is exhibited by subjects who show elevated peak responses to active coping stressors specifically.     

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.     

Habituation of Fear: Effects of Intensity and Stimulus Order

This study investigated snake-fearful subjects' skin conductance, heart rate, and fear ratings to repeated presentations of seascape and snake films (10–13 sec duration). The films sampled three levels of fear intensity and were displayed in ascending, descending, or nonsystematic orders; additional Ss viewed only high-fear material. A linear relationship with fear intensity emerged for fear ratings, but not for physiological measures. Differences found between orders in patterns of habituation were concordant for cardiac rate and fear ratings; relative to the other orders, the ascending sequence habituated less and displayed sensitization to material of higher fear levels. In all orders, there was marked habituation of physiological responses, especially in the first session. The possible role of adaptation level and implications of the data for desensitization and flooding were noted.     

Recovery from stress: an experimental examination of focused attention meditation in novices

Identifying strategies that aid in recovery from stress may benefit cardiovascular health. Ninety-nine undergraduate meditation novices were randomly assigned to meditate, listen to an audio book, or sit quietly after a standardized stressor. During recovery, meditators’ heart rate variability and skin conductance levels returned to baseline, whereas only heart rate variability returned to baseline for the audio book and control groups. Positive and negative affect were no different than baseline following meditation, whereas, both audio book and control groups had lower positive affect and higher negative affect following the intervention. Findings suggest that the sympathetic nervous system is uniquely affected by meditation, and novices may benefit emotionally from meditating after a stressor. Further research is needed to determine meditation’s utility in recovering from stress.     

Individual differences in overextincation of the SCR component of the orienting response

The present study investigated individual differences in overextinction of the skin conductance response (SCR) component of the orienting response. On the basis of Sokolov's (1963) proposal that overextinction is accompanied by drowsiness, two hypotheses were formulated: (a) subjects exhibiting overextinction will display lower levels of skin conductance and spontaneous activity during the return period than subjects who show no response return, (b) overextinction in the return group will be accompanied by a fall in both skin conductance level and spontaneous activity. Neither of these hypotheses was supported. The results did indicate, however, that the return group displayed slower initial habituation rates and more spontaneous activity than the non-return group. Within the return group, speed of response return was positively related to both spontaneous activity at rest and number of stimuli required for initial habituation, and negatively related to mean SCR latency during initial habituation.     

Psychophysiological Correlates of Electrodermal Lability

This study of 75 college student subjects investigated the psychophysiological correlates of electrodermal lability. Resting-stabile and resting-labile subjects were defined as those who were respectively below and above the median of all same-sex subjects in frequency of nonspecific skin conductance responses during rest, whereas stimulus-stabile and stimulus-labile subjects were those respectively below and above the median in trials to habituation of the skin conductance orienting response. These two classification systems were found to be highly correlated with one another, but not entirely equivalent. With both lability measures, labiles had higher resting skin conductance levels than stabiles and also exhibited larger skin conductance orienting responses to both signal and nonsignal tones. Labiles produced orienting responses with shorter latencies, rise times, and half recovery-times. Resting-labiles also differed from resting-stabiles in the components of the triphasic heart rate response to the tones, having larger decelerative responses. The data are consistent with the view that labiles are better able than stabiles to allocate attentional capacity to environmental events and to respond to changing demands in an attentional situation.     

Cardiovascular and Electrodermal Responses Conditioned to Fear-Relevant Stimuli

This study examined heart rate, finger pulse volume, and skin conductance responses in subjects conditioned to fear-relevant (snakes and spiders) and fear-irrelevant (flowers and mushrooms) slide stimuli by an electric shock unconditioned stimulus. A differential conditioning paradigm with an interstimulus interval of 8 sec was used. There were 4 habituation, 8 acquisition, and 20 extinction trials with each of the two cues. The results demonstrated reliable acquisition for finger pulse volume and skin conductance responses, with superior resistance to extinction for the fear-relevant conditioned stimuli. The heart rate data showed no differentiation between reinforced and nonreinforced cues during acquisition and extinction, and no effect of fear-relevance. This discrepancy between skin conductance and finger pulse volume responses, on the one hand, and heart rate, on the other, was interpreted as due to differences in innervation, with the former measures mainly reflecting sympathetic and the latter parasympathetic effects.     

Repeated acoustic stimulation of acute schizophrenic patients and the habituation of EEG power changes

Habituation in psychiatric patients to repeated stimuli has typically been described in connection with the measurement of the skin conductance orienting response. Here EEG power spectra of acute schizophrenic patients and normals to 4 trials of an acoustic stimulation were examined for evidence of habituation. In response to stimulation the alpha EEG reactivity was less distinct in schizophrenics than in normals. This is in agreement with the theory of hypovariability or hyperstability of the EEG in schizophrenics. Signs of habituation in acute schizophrenics were clearer in fast beta frequencies of the parietal leads.     

THE EVOKED HEART RATE RESPONSE: THE INFLUENCE OF AUDITORY STIMULUS REPETITION, PATTERN REVERSAL, AND AUTONOMIC AROUSAL LEVEL

A brief two-component auditory stimulus was repeatedly presented at 10-sec intervals to 48 college students. Analysis of the pattern of sec-by-sec changes in heart rate (HR) revealed that the only reliable response to the first stimulus was HR deceleration. During the remainder of the first 20 trials, an acceleration was the predominant response in the HR curves. When the stimulus pattern was reversed on trial 21 to study “dishabituation,” only a HR deceleration was again observed. A significant habituation effect appeared across trials employing an index based upon the difference between peak and trough values. Further analysis revealed that the two response components reflected in the peak and trough values of this index showed different rates of response decrement. The acceleratory component showed a rapid initial decrement and remained stable on subsequent trials, whereas the deceleratory component diminished more gradually. Level of autonomic arousal, as measured by skin conductance level, was unrelated to HR habituation.