Overhabituation and Dishabituation Responses as a Function of Stimulus Intensity and Amount of Overhabituation Training

Several important issues regarding overhabituation and its effects have been raised. Of particular interest are the effects of amount of overhabituation on responses during overhabituation, the existence of important individual differences in response frequency and amplitude during overhabituation, and the effect of varied amounts of overhabituation training and of stimulus intensity on test and dishabituation response amplitudes. In the present study, each of 108 subjects was randomly assigned to one of three overhabituation exposure conditions (60, 120, or 180 trials) and one of two auditory stimulus intensities (60 or 85 dB). After reaching a phasic electrodermal habituation criterion, each subject received the appropriate number of overhabituation presentations of the standard stimulus (SS), followed by a test stimulus and an additional SS (the dishabituation stimulus). Results showed significantly higher frequencies and amplitudes of electrodermal responses to tonal stimuli with increasing numbers of overhabituation trials, but no significant changes over trial blocks. Individual differences were found. Subjects in a group defined by numerous overhabituation responses showed slower habituation, larger responses and higher frequencies of nonspecific responses during overhabituation, and larger test responses. Finally, the amplitude of test responses increased with increasing length of overhabituation and with increased intensity.     

Electrodermal Activity in Hyperactive Boys Who Are Methylphenidate Responders

Hyperactive boys being treated with methylphenidate medication were randomly divided into two groups. In one of the hyperactive groups (n = 18) methylphenidate was withheld for approximately 72 hrs before testing. Boys in the other hyperactive group (n = 20) continued to take their usual daily doses of methylphenidate. Normal boys formed a third group (n = 20). The following electrodermal measures were taken: basal resistance, frequency of non-specific responses, specific response amplitude to an auditory signal, and number of trials to habituation. Normal and off-drug hyperactive groups differed significantly on specific response amplitude, and trials to habituation. In addition, frequency of non-specific responses approached significance. These differences indicated lower reactivity in the off-drug hyperactive group. Off-drug and on-drug hyperactive groups differed significantly on frequency of non-specific responses. In addition, trials to habituation approached significance. These differences again indicated lower reactivity in the off-drug hyperactive group.     

Effects of Arousal on Habituation of Electarodermal versus Vasomotor Responses

While there is considerable evidence (hat habituation of electrodermal responses is retarded under conditions of heightened arousal, less work has been done on vasomotor responses. A few studies have, however, suggested that arousal has the opposite effect on vasomotor responses, producing an acceleration of habituation In this case. The present study compared skin conductance (SC) and finger pulse volume (PV) responses to a series of tone stimuli under conditions of “high arousal” (HA)-where subjects were standing during testing-and “low arousal” (LA)-where subjects were seated. Tonic measures confirmed that the experimental manipulation was effective in raising SC level and nonspecific activity and lowering PV level in the HA relative to the LA condition. Significant Group (HA vs. LA) X Measure (SC vs. PV) interactions for response frequency and number of trials to habituation were consistent with the prediction that arousal exerts differential effects upon habituation in the two response systems. These data provide further challenges to theories based on unitary models of autonomic response mechanisms.     

Learning to fear suffocation: a new paradigm for interoceptive fear conditioning

The present study aimed to establish a new interoceptive fear conditioning paradigm. The conditioned stimulus (CS) was a flow resistor that slightly obstructs breathing; the unconditional stimulus (US) was a breathing occlusion. The paired group (N = 21) received 6 acquisition trials with paired CS–US presentations. The unpaired group (N = 19) received 6 trials of unpaired CS–US presentations. In the extinction phase, both groups were administered 6 CS‐only trials. Measurements included startle eyeblink response, electrodermal responses, and self‐reported US expectancy. In the paired group, startle blink responses were larger during CS compared to intertrial interval during acquisition and extinction. Electrodermal and US expectancies were larger for the paired than for the unpaired group during acquisition, but not during extinction. The present paradigm successfully established interoceptive fear conditioning with panic‐relevant stimuli.     

Scoring Criteria for Response Latency and Habituation in Electrodermal Research: A Study in the Context of the Orienting Response

Levinson and Edelberg's (1985) recent critique of scoring criteria for electrodermal studies pointed to the need to reduce the latency range used to define the electrodermal response. The present study examined the impact of such a narrowing of the latency window upon habituation and instructional effects in studies of the orienting response to low intensity innocuous stimuli. The first experiment found only a small effect of halving the latency window upon habituation to neutral stimuli, apparent as a strengthening of trends over trials. A second experiment showed somewhat larger effects with significant stimuli, apparent as slightly modified trial and group effects. These data support the view that nothing is to be lost by moving to a narrower latency range to define the electrodermal orienting response to stimulus presentation, and suggest that the advantages of such a change will become increasingly important as nonspecific electrodermal fluctuations increase with increasing electrodermal arousal. An analysis of habituation criteria within this context suggested that the choice of two rather than three no-response trials to define habituation adds to the benefits obtained by the selection of a narrow latency window to define the response.     

Short-, Medium-, and Long-Term Relationships Among Meteorological and Electrodermal Variables

The present study investigated the relationship between weather and electrodermal data. The latter were gathered during three habituation studies with a common initial procedure: male undergraduates (N = 336) were presented with a 1-sec, 500 Hz, 55 dB tone until habituated. Initial skin conductance level (SCL), mean square root skin conductance response to the first 3 tones (√SCR), and number of trials to SCR habituation (TH) were each correlated with the meteorological conditions (temperature, relative humidity, and barometric pressure) during each of several pre-experimental periods lasting from 1 hr to 1 month. The multiple correlation (R) between SCL and the meteorological variables was low but statistically significant for each time period, as was the case for √SCR. For TH the Rs were significant only for time periods of 1 day or more. Cross-validations indicated that the Rs were stable and that electrodermal values could be reliably predicted from meteorological data. These results, together with correlations of each meteorological variable with each electrodermal variable and examinations of each variable across academic semesters, indicated that meteorological variables bear significant and complex relationships to electrodermal activity which warrant consideration in the design of experiments with extended data collection periods.     

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.     

Scoring Criteria for Response Latency and Habituation in Electrodermal Research: A Critique

Recent evidence, particularly in research on the skin conductance orienting response (SCOR) in schizophrenia, suggests that differences in scoring criteria may be important sources of error and variability in studies of electrodermal responses to discrete stimuli and their habituation. Although a wide variety of response latency criteria have been used in published studies, empirical evidence suggests that responses occur in a narrow and early post-stimulus time window. Data are presented demonstrating that the intra-subject variability of response latency is low when responses are scored within a narrow time window, but that broader time windows include more variable-latency responses that may represent spontaneous activity. The commonly-used criterion of three no-response trials as an habituation endpoint may also introduce contamination by spontaneous activity; available evidence favors a two-trials criterion. Analyses such as the ones presented here permit testing of the specificity of scoring criteria for responses elicited by experimental stimuli.     

Baseline and affective startle modulation by angry and neutral faces in 4-8-year-old anxious and non-anxious children

The present study examined the magnitudes of startle blink reflexes and electrodermal responses in 4-8-year-old high anxious children (N=14) and non-anxious controls (N=11). Responses were elicited by 16 auditory startle trials during a baseline phase prior to an affective modulation phase involving 12 startle trials presented during angry and neutral faces. Results showed significant response habituation across baseline trials and equivalent response magnitudes between groups during the baseline phase. The modulation of response magnitudes during angry and neutral faces did not differ significantly in either group. However, high anxious children showed larger responses overall compared with non-anxious control children during the affective modulation phase. Moreover, greater anxiety severity and larger startle reflexes were associated with poorer accuracy in rating neutral faces as neutral in high anxious children. Results may reflect elevated reactivity to threat contexts in 4-8-year-old high anxious versus non-anxious children.     

Time of Quarter Effect: An Uncontrolled Variable in Electrodermal Research

Does the time of the academic quarter in which a subject participates in an electrodermal habituation study have an effect upon electrodermal response components—e.g., skin conductance level (SCL), skin conductance response (SCR), and spontaneous fluctuation (SF) activity? Four groups of 24 undergraduates (12 males and 12 females each) participated in an habituation session consisting of a 10-min adaptation period and 15, 5-sec bursts of 85 dB white noise, during the first, fourth, seventh, or tenth week of an eleven-week quarter. Predictably, all three dependent variables were affected by the time of quarter (TOQ) manipulation and/or by the interaction of this variable with the sex of the participant. Relationships between three meteorological variables—temperature, humidity, and barometric pressure—and the electrodermal variables were also quantified. Several of the correlations between these meteorological variables and the electrodermal measures were found to be significantly greater than zero; however, when employed as covariates, these meteorological variables failed to significantly modify the effects of the independent variable manipulations upon the electrodermal measures. Results are discussed in terms of the need to adequately control for this potentially confounding variable in electrodermal research.     

ONSET AND TERMINAL ORIENTING RESPONSES AS A FUNCTION OF TASK DEMANDS

The frequency of response and trials to habituation of the electrodermal onset and terminal orienting response were manipulated as a function of discrimination tasks involving either stimulus content (pitch) or duration. There were no significant differences between the groups on either measure for onset ORs; however, the duration task group demonstrated more TORs and required a greater number of trials to habituate than the content task group. The results, interpreted in terms of the development of cortical models, supported Stern's suggestion that OR and TOR habituation are related to the content and duration of the stimulus respectively.     

Arousal modulation of memory and amygdala-parahippocampal connectivity: a PET-psychophysiology study in specific phobia

Phobic fear is accompanied by intense bodily responses modulated by the amygdala. An amygdala moderated psychophysiological measure related to arousal is electrodermal activity. We evaluated the contributions of electrodermal activity to amygdala-parahippocampal regional cerebral blood flow (rCBF) during phobic memory encoding in subjects with spider or snake phobia. Recognition memory was increased for phobia-related slides and covaried with rCBF in the amygdala and the parahippocampal gyrus. The covariation between parahippocampal rCBF and recognition was related to electrodermal activity suggesting that parahippocampal memory processes were associated with sympathetic activity. Electrodermal activity further mediated the amygdala effect on parahippocampal activity. Memory encoding during phobic fear therefore seems contingent on amygdala's influence on arousal and parahippocampal activity.     

Habituation of the Skin Conductance Response to Strong Stimuli: A Twin Study

Skin conductance responses to a series of loud tones were measured bilaterally in 121 pairs of adult twins, 53 pairs reared together and 68 pairs reared apart. Subjects were given an absorbing task on which to focus their attention and instructed to ignore the meaningless tones. Rangecorrection eliminated hand and sex differences in SCR amplitude and also the correlation with age of this variable. For the combined group of 79 pairs of monozygotic (MZ) twins, the within-pair correlations for Y-intercept, the slope of the habituation curve, and the number of trials to habituation were near the limits of retest reliability for these variables. After range-correction, the correlation for Y-intercept for the 42 pairs of dizygotic (DZ) twins was about half the MZ value, suggesting that initial electrodermal reactivity is strongly genetic and can be interpreted according to a polygenic-additive model. Biometric model testing indicated that stable individual differences in uncorrected SCR amplitude and in habituation slope are primarily determined by non-additive genetic factors. About 40% of the total variance (and most of the stable variance) in number of trials to habituation is genetically determined. Co-twins of MZ twins who were electrodermal nonresponders tended also to be hyporesponsive while co-twins of DZ nonresponders tended to be normoresponsive.     

Electrodermally differentiated subgroups of anxiety patients. I. Automatic and vigilance characteristics

A total of 32 anxiety patients (agoraphobia, panic syndrome, generalized anxiety syndrome) selected according to the DSM-III criteria were compared with 16 controls to determine distinguishing features of autonomic response patterns to a sequence of verbal and acoustic stimuli. In addition sensorimotor tasks were performed. The anxiety patients were classified into electrodermally stabile and labile subgroups on the basis of two reliably measurable psychophysiological parameters: the rate of electrodermal habituation to neutral stimuli and non-specific electrodermal activity. The electrodermally labile anxiety group was characterized by a high degree of variability in respiratory and pulse rate during the autonomic activation procedure. Within the control group the electrodermally labile subjects were characterized by a significantly higher pulse rate during the entire autonomic activation procedure. The reduced habituation capacity of the labile subgroup of anxiety patients compared to the controls was reflected in both retarded habituation and long durations of electrodermal responses to all verbal stimuli. This group also tolerated monotony; their performance did not drop during the 256 sensorimotor reaction time tasks and even exceeded the performance of the control group by the end of the test. The stabile anxiety subgroup had a significantly longer reaction time in all reaction time tasks than the labile subgroup of anxiety patients.     

The Electrodermal Orienting Response and Memory: An Analysis of Age Differences in Picture Recall

Young and elderly women were compared on electrodermal measures of the orienting response (OR) to picture stimuli presented during the study phase of a free recall task. Responses were also recorded during a subsequent simple habituation paradigm which was designed to investigate stimulus priming effects. Young subjects recalled more pictures than the elderly and both groups remembered more pictures with common word names than pictures with uncommon verbal labels. Young and older subjects displayed larger skin conductance responses to recalled pictures, especially to recalled uncommon pictures. Older women, however, displayed consistently smaller SCRs than the young. Stimulus priming was observed on the first trial of habituation training where not-recalled pictures evoked smaller SCRs than pictures not shown in the study phase. There were no age differences in habituation across trials. In general, the results indicated that the electrodermal OR is functionally related to recall performance and that the age decrement in recall may be attributed to reduced cognitive effort in the elderly.     

Physiological reactivity as a predictor of performance in a vigilance task

The experiment was designed to determine the value of measures of physiological activity as predictors of performance in a vigilance task. Subjects, for whom resting (EEG, heart rate, and skin conductance) and response (electrodermal) measures were available, were given an auditory vigilance task. Overall vigilance performance was significantly correlated with one measure of electrodermal habituation, latency of response to the first of a series of stimuli, and total number of responses to stimuli. None of the measures of resting physiological activity were significantly related to vigilance performance. The results are discussed in terms of Mackworth's (1969) theory of vigilance.     

Augmented sympathetic nerve activity in response to stressors in young borderline hypertensive men

To determine whether there may be an abnormality in sympathetic nerve activity in response to physical and psychological stressors, we microneurologically recorded muscle sympathetic nerve activity in 11 normotensive and 9 borderline hypertensive, age-matched men. Supine blood pressure, plasma levels of epinephrine and norepinephrine and muscle sympathetic nerve activity were measured before and during a cold pressor test or a mental arithmetic test. The resting basal values of muscle sympathetic nerve activity, blood pressure and plasma epinephrine were significantly higher in the borderline hypertensives than in the normotensives (P less than 0.05). Plasma norepinephrine levels tended to be higher in the borderline hypertensives than in the normotensives but not to a significant extent (P less than 0.10). The cold test produced significantly exaggerated pressor and muscle sympathetic nerve responses (P less than 0.05) with a trend towards an increase in plasma norepinephrine (P less than 0.10) in the borderline hypertensives as compared with normotensives. The mental arithmetic test produced significantly enhanced pressor and plasma epinephrine responses in the borderline hypertensives as compared with the normotensives (P less than 0.05). During the mental arithmetic test the muscle sympathetic nerve activity decreased significantly in the normotensives (P less than 0.05) but not in the borderline hypertensives. These findings indicate that in people with borderline hypertension an abnormality exists in sympathetic nerve activity at rest and in response to stressors.     

CLASSICAL CONDITIONING OF THE ELECTRODERMAL RESPONSE WITH NOVEL STIMULI

Most attempts to classically condition the electrodermal response (GSR) have used aversive stimuli. A series of 20 novel slides were used as unconditional stimuli in a delayed differential conditioning paradigm involving reinforced and unreinforced conditional stimuli. Thirty female Ss were given 10 habituation trials, 40 conditioning trials of which half were reinforced, and 10 extinction trials. Orienting response, anticipatory response, and post-conditional stimulus response components were analyzed separately for the different series. Differential conditioning was obtained for two of the responses during the conditioning and extinction series. The results indicate that a relatively mild novel stimulus can also effectively condition the GSR.     

Electrodermal and phasic heart rate responses in the Guilty Actions Test: Comparing guilty examinees to informed and uninformed innocents

The present mock-crime study concentrated on the validity of the Guilty Actions Test (GAT) and the role of the orienting response (OR) for differential autonomic responding. N=105 female subjects were assigned to one of three groups: a guilty group, members of which committed a mock-theft; an innocent-aware group, members of which witnessed the theft; and an innocent-unaware group. A GAT consisting of ten question sets was administered while measuring electrodermal and heart rate (HR) responses. For informed participants (guilty and innocent-aware), relevant items were accompanied by larger skin conductance responses and heart rate decelerations whereas irrelevant items elicited HR accelerations. Uninformed participants showed a non-systematic response pattern. The differential electrodermal responses of informed participants declined across the test. With respect to the HR data, however, no habituation was observed. Findings suggest that GAT results could not exclusively be interpreted by referring to the OR.     

The cardiac responses of schizophrenics to orienting, signal and non-signal tones.

The cardiac responses of schizophrenics were examined under three conditions: (1) to repeated 75 dB, 1000 Hz (orienting) tones of no attentional significance; (2) to 75 dB, 1000 and 2000 Hz tones presented randomly and requiring a motor response to the 1000 Hz (signal) tone; (3) to 85 dB, 1000 Hz orienting tones. Responses of non-psychotic psychiatric patients were examined to the 75 dB tones. All patients were subdivided upon the basis of electrodermal responsivity during conditions (1) and (3), into groups of responders - no habituation of responses; non-responders - no responses; habituators - responses habituated to criterion. All groups exhibited a decelerative response with a latency of less than 1 sec. The groups were differentiated by the second component of the response to the orienting tones: responders - acceleration; habituators - deceleration; non-responders - predominantly no response. All exhibited accelerative responses to the signal tones. Parallels between cardiac and electrodermal responsivity are outlined.