The Psychophysiology of Sensation Seeking Manrin Zuckermon University of Delaware ABSTRACT This article summanzes studies relating the trait of sensation seeking to electrodermal and heart-rate responses and cortical evoked potential arousal Stimulus factors of novelty, mtensity, and stimulus significance are important High sensation seekers tend to give stronger physiological onentmg responses than lows to novel stimuh of moderate intensity, particularly when such stimuli are of specific interest Lows tend to show defensive responses as defined by heart-rate acceleration The cortical reaction of the highs tends to be augmented by intense visual or auditory stimuh, while that of the lows tends to be reduced or unresponsive to variations in stimulus intensity Differences between psychophysiological responses of high and low sensation seekers are interpreted as reflective of different evolved biological strategies for processing novel or intense stimulation Sensation seeking has been defined as a human trait characterized by the need for "vaned, novel, and complex sensations and expenence and the willingness to take physical and social risks for the sake of such expenence" (Zuckerman, 1979, p 10) Intensity of sensation should have been mcluded in this definition as well Although the trait has been largely conceptualized and investigated at the human level, studies m comparative psychology have explored possible neuropsychological and psychopharmacological bases of the trait (Zuckerman, 1984a, 1984b, 1987b) It is my convicUon that the human trait is based in some significant part on inherited differences in the structure and biochemistry of the central nervous system, but expenmental approaches to these basic aspects of biological traits in humans are rare Psychophysiological approaches, however, are more apphcable to humans and a growing Requests for refmnts and other communications regarding this article should be addressed to Marvm Zuckerman, Department of Psychology, University of Delaware, Newaric, DE 19716 Joumal cfPersonality 58 1, March 1990 Copynght © 1990 by Duke Umversity Press CCC 0022-3506/90/$! 50
314
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literature on the applications of these methods to the trait of sensation seeking will be described in this article I have suggested that sensation seekmg is a trait that has evolved as a function of its adaptive value for survival and reproductive fitness Novel stimuli may elicit either approach or avoidance reactions depending on species, level of maturation, and individual differences within species Schneirla (1959) used the terms approach and withdrawal to descnbe reflexive, tropistic, and instinctive responses to stimulation He used the terms seeking and avoidance to descnbe the more complex behavioral pattems m more complex organisms which are relatively more modifiable by leammg expenences Schneirla related A-type (approach) behavior to activity directed at obtaining food, shelter, and mates, while W-type (withdrawal) behavior is characterized by defensive adjustments including freezing, huddhng, and flight According to Schneirla, high-intensity stimulation tends to elicit W-type responses while low to moderate stimulation results in A-type behavior I suggest that individual differences m reactivity to intense and novel stimulation, that provide the basis for the sensation-seeking trait, may be the end result of natural vanation in evolved A and W mechanisms in humans Sensation seeking and sensation avoidance, as extremes of a continuous behavioral trait dimension, may represent two different strategies for adaptation to a dangerous environment m which novel stimuh can be either sources of biological reward or a threat to survival The sensation seeker among our hominid ancestors was probably more exploratory and more adventurous than the sensation avoider This trait pattem would provide the advantage of increased access to new potential food sources and mates, but a disadvantage in terms of the nsks entailed in such activities The sensation avoider would tend to avoid the nsks at the expense of the loss of foraging and reproductive advantage An interesting parallel can be found in studies of the green iguana by Phillips (reported by Browne, 1988) Iguanas compete for basking places m the sun The choice places are occupied by the more dominant males and their sisters The subordinate males tend to stay out of sight to avoid encounters with the dominants The larger, more dominant males are more successful at mating However, by spending more time exposed in the open they are also more vulnerable to eagles and other prwiators, including humans (large iguanas are favored by humans as a source of meat) Conservationists trying to replenish the shrinking population of iguanas are uncertain as to whether they should breed and tum loose the dominants or subordinates of the species As with many traits, the extremes would be maladaptive and some
Psychophysiology of Sensation Seeking
315
optimal range of the trait nught have been of evolutionary advantage Of course, this would have tended to nanow the vanation in the trait But if the trait were a basis for assortative mating (mate choice based on similanty of some charactenstic) and based on poly genetic inhentance, the assortative mating would cause an increase in genetic vanance (Wilson, 1975) that could offset any disadvantage in the extreme manifestations of the trait Finally, there is the possibility that the trait is an incidental by-product of genetic variance that exists for some other reason and has never been strictly functional or adaptive (Buss, 1990) This kind of sociobiological speculation is interesting but largely post hoc Although It descnbes a possible source of selection for the trait m evolutionary history its relevance to current adaptation in the complex societies of today is questionable However, the theory does suggest that we might find hentable biological markers for the trait in currently extant organisms Sensation seeking has been shown to have relatively high hentability for a personality trait (Fulker, Eysenck, & Zuckennan, 1980) There is a high degree of assortative mating for the trait (Farley & Davis, 1977, Farley & Mueller, 1978), and the degree of congruence of the trait in marital partners is related to their mantal adjustment (Ficher, Zuckerman, & Neeb, 1981, Ficher, Zuckerman, & Steinberg, 1988) Sensation seeking has been related to engagement m a variety of nsky activities and to the extent and variety of heterosexual expenence (Zuckerman, 1979, Zuckerman, Tushup, & Finner, 1976) What I suggest is that certain psychophysiological mechanisms, that are themselves strongly hentable, may provide biological markers for Schneirla's A and W tendencies in humans and constitute part of the biological basis for the sensation-seekmg trait In one sense most of this research is correlational and cannot establish the etiological role of the psychophysiological trait m the psychological one Both may be regarded as functions of some common central mechanism What IS vaned in most of these expenments are the stimulus factors of intensity, novelty, and meaning Developmental studies suggest that the mteraction of temperament with reactivity to these stimulus factors appears early in life before much socialization has taken place Thomas and Chess (1977) use "Approach or Withdrawal" as one of their nine categories of temperament m infancy The dimension is defined as "the nature of the mitial response to a stimulus, be it a new food, new toy, or new person" (p 21) Assessments of this dimension of temperament at ages 3 and 4 i^edicted adult temperament, although the correlations were low (Thomas & Ctess, 1986) Kagan, Reznick, and Smdman (1988) report that high and stable
316
Zuckerman
heart rates and heart-rate acceleration to novel or cognitive stimuli from 21 months of age and older were significantly related to inhibited versus uninhibited behavior at 5 5 and 7 5 years of age Heart-rate patterns were reliable from 21 months to 7 5 years Pupillary dilation, another index of sympathetic activity, was also related to the trait of inhibition versus lmpulsivity In this article, I will review psychophysiological pattems of response to stimulus vanations in novelty, intensity, and meamng in high and low sensation seekers usmg three types of physiological response electrodermal and heart-rate responses and cortical evoked potentials Although tonic levels of arousal have played a major role in Eysenck's (1967) theory of Extraversion, we have found that specific kinds of arousability rather than general arousal are more important for the trait of sensation seeking While the concept of general arousal or arousability has been useful for theory building, the facts suggest that psychophysiological systems show individual response and stimulus-specific pattems so that it is nearly impossible tofinda pattem of general arousal applicable to all or most persons (Zuckerman, 1987a, Zuckerman & Como, 1983) For this reason, I will discuss the three psychophysiological systems separately and end with an attempt to interpret the results for all three in terms of pattems of adaptation specific to high and low sensation seekers
Sensation Seeking Scales (SSS) The SSS has been used as the standard test instrument for defining the trait of sensation seeking The initial version of the scale (SSS II, Zuckerman, Kolin, Pnce, & Zoob, 1964) contained only a general scale, derived from an initial factor analysis, with items expressing a desire to engage in activities providing excitement, nsk, and novelty or a preference for stimuh and people with these characteristics Subsequent factor analyses (Zuckerman, 1971), including more items, yielded four subscales (a) Thnll and Adventure Seeking, or the desire to engage in nsky physical activities or sports providmg unusual sensations, (b) Expenence Seeking, or the desire to seek new experience through the nund and senses and through an unconventional life-style and travel, (c) Disinhibition, or the seeking of sensation through other people or partying, social drinking, and sex, and (d) Boredom Susceptibility, or an aversion for unchanging or unstimulating environments or persons The most widely used current form of the SSS (Form V, Zuckerman,
Psychophysiology of Sensation Seeking
317
S B G Eysenck, & H J Eysenck [1978]), based on further factor analyses in England, is a shortened form of Form IV, using the most consistently loading items on the factors It also has a total score based on the sum of the four subscales The forms of the SSS have been translated into many languages and factor analyses in several countnes have essentially confirmed the four factors, although some items have shifted from one factor to another Onenting, Defense, a n d Startle Reflexes In discussing the psychophysiological responses to stimuli I will be making distinctions between three types of reaction orienting reflex, defensive reflex, and startle reflex The distinction between the first two, as elucidated by Sokolov (1963) and Graham (1979), involves the difference between responses that enhance sensitivity to external stimuli (onenting reflex) and those that reduce sensitivity (defensive reflex) Others have suggested that the defensive reflex, typically elicited by high intensities of stimulation, represents preparation for physical activity The startle reflex seems to represent an "interrupt" system m response to strong and unanticipated stimuli It is difficult to distinguish the three types of responses, except by reference to stimulus factors in uniphasic measures like skin resistance or conductance changes However, Graham (1979) has descnbed different charactenstics for defining the reflexes in heart-rate responses to stimuh The startle reflex is a short latency increase in heart rate, the defensive reflex is a long latency heart-rate increase, and the onenting reflex is a prolonged (2to 4-s) heart-rate decrease The relative strength of these types of responses could represent an important biological marker for personality differences Electrodennal Reactivity Three aspects of electrodermal reactivity will be discussed The tonic level of activity, or skm conductance level (SCL), reflects the electrodermal arousal just before or dunng the expenmental situation The phasic level, defined by the skin conductance response (SCR) measure, IS the amplitude of response to a given stimulus When the same stimulus IS presented a number of times m succession, one usually sees tiie strongest response to the first presentation and a diminished response with each subsequent presentation until there is no measur-
318
Zuckennan
able response This process is called habituation and may be measured m terms of tnals to extinction or slope of the regression line of response amplitude on tnals These measures are listed in Table 1 for nine expenments m eight studies Differences in tonic electrodermal arousal (SCL) between high and low sensation seekers have seldom been found, and when they do occur they are specific to certam conditions or subscales of the SSS In the studies by Smith, Perlstem, Davidson, and Michael (1986) and Stelmack, Plouffe, and Falkenberg (1983) high sensation seekers were more aroused (higher SCL) dunng conditions when words were presented as stimuli than dunng other stimulus conditions Nothing m the theory of sensation seeking explains this kmd of arousal specific to semantic stimuli Cox (1977) showed that high sensation seekers did not differ from lows at the beginning of a 70-mm penod of isolation m relatively depnved stimulus conditions, but the highs were lower in SCL at the end of the penod as a consequence of dropping in arousal, while the lows stayed the same over the penod This makes more sense in terms of the ongmal theory of sensation seeking (Zuckerman, 1969) that suggested stronger cortical inhibitory systems in highs However, an earlier study of electrodermal response to sensory depnvation (Zuckerman et al , 1966) did not yield differences between high and low sensation seekers, although the highs did become more restless m confinement conditions as reflected m body movements In the Robinson and Zahn (1983) study the highs on the Dismhibition subscale of the SSS showed higher SCLs than the lows, but the difference was not found when the general SSS was used to define high and low groups Five of the eight studies (Feij, Orlebeke, Gazendam, & van Zuilen, 1985, Neary & Zuckerman, 1976, Robinson & Zahn, 1983, Smith et al , 1986, Stelmack et al , 1983) found some evidence that high sensation seekers gave a stronger SCR, or onenting reflex, to the first presentation of a visual or auditory stimulus in a senes Figure 1 shows the results of the first expenment by Neary and Zuckerman (1976) to 10 presentations of a simple visual stimulus (rectangle) followed immediately by 10 presentations of a new stimulus (abstract design) Tlie male high sensation seekers responded more strongly than the lows to the first presentations of both stimuh, but for second presentations they immediately dropped to the level of the lows and habituated at the same rate to subsequent stimuh In further studies if differences occurred, the highs usually responded
Psychophysiology of Sensation Seeking
319
more than the lows when the stimulus was novel, but they responded at the same level as lows to second and subsequent presentations The exception was the study by Smith et al (1986) in which the stimuli withm a class were vaned and had content of specific interest to high sensation seekers The evidence from Stelmack et al (1983) is problematical for the sensation seekmg-electrodermal orienting reflex relationship since It was in opposite directions for two classes of visual stimuli, and the positive relationship with the word stimuli was not significant after controlling the SCR for SCL Three studies (Cox, 1977, Ridgeway & Hare, 1981, Zuckerman, Simons, & Como, 1988) did not support a sensation seeking-onentmg reflex relationship Even in the studies where there was a relationship, it was weak (r = 28 m Feij et al [1985], and 26 in Stelmack et al [ 1983]) More robust results were obtained in the Smith et al (1986) study in the form of highly significant interactions, and sometimes main effects, of sensation seeking and stimulus content The onenting reflex is an index of interest or focused attention on a particular stimulus In this case the stimulus meaning had positive value for high sensation seekers since it depicted activities or objects they value Based on studies of animals (mostly rodents) Gray (1973, 1982) has linked the orienting reflex to novel stimuh with anxiety, while I have suggested that the onenting reflex in humans is more often related to positive interest and arousal (Zuckerman, 1982, 1984a) In some of these studies the investigators examined the interaction of sensation seeking with trait and/or state anxiety in electrodermal responsivity Neary and Zuckerman (1976) selected subjects high or low on the four combinations of sensation seeking and trait anxiety While trait anxiety had no effect on electrodermal response, either alone or m interaction with sensation seeking, a state anxiety scale given just before the expenment began was related to response to both novel (first presentations) auditory sUmuh, and one ofthe two novel visual stimuh State anxiety was not related to sensation seeking so the effects of both were independent Subjects reporting high state anxiety gave weaker SCRs to the novel stimuh than those low m anxiety just pnor to the expenment Robmson and Zahn (1983) used the state anxiety scale from the State Trait Anxiety Inventory (Spielberger, Gorsuch, & Lushene, 1970) along with the SSS in selecting subjects They found significant interactions between anxiety and sensation seeking with low anxietyhigh sensatKjn-seekmg subjects manifesting the highest amplitudes of response to novel tones and fastest latencies, and the high anxiety-
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literature on the applications of these methods to the trait of sensation seeking will be described in this article I have suggested that sensation seekmg is a trait that has evolved as a function of its adaptive value for survival and reproductive fitness Novel stimuli may elicit either approach or avoidance reactions depending on species, level of maturation, and individual differences within species Schneirla (1959) used the terms approach and withdrawal to descnbe reflexive, tropistic, and instinctive responses to stimulation He used the terms seeking and avoidance to descnbe the more complex behavioral pattems m more complex organisms which are relatively more modifiable by leammg expenences Schneirla related A-type (approach) behavior to activity directed at obtaining food, shelter, and mates, while W-type (withdrawal) behavior is characterized by defensive adjustments including freezing, huddhng, and flight According to Schneirla, high-intensity stimulation tends to elicit W-type responses while low to moderate stimulation results in A-type behavior I suggest that individual differences m reactivity to intense and novel stimulation, that provide the basis for the sensation-seeking trait, may be the end result of natural vanation in evolved A and W mechanisms in humans Sensation seeking and sensation avoidance, as extremes of a continuous behavioral trait dimension, may represent two different strategies for adaptation to a dangerous environment m which novel stimuh can be either sources of biological reward or a threat to survival The sensation seeker among our hominid ancestors was probably more exploratory and more adventurous than the sensation avoider This trait pattem would provide the advantage of increased access to new potential food sources and mates, but a disadvantage in terms of the nsks entailed in such activities The sensation avoider would tend to avoid the nsks at the expense of the loss of foraging and reproductive advantage An interesting parallel can be found in studies of the green iguana by Phillips (reported by Browne, 1988) Iguanas compete for basking places m the sun The choice places are occupied by the more dominant males and their sisters The subordinate males tend to stay out of sight to avoid encounters with the dominants The larger, more dominant males are more successful at mating However, by spending more time exposed in the open they are also more vulnerable to eagles and other prwiators, including humans (large iguanas are favored by humans as a source of meat) Conservationists trying to replenish the shrinking population of iguanas are uncertain as to whether they should breed and tum loose the dominants or subordinates of the species As with many traits, the extremes would be maladaptive and some
Psychophysiology of Sensation Seeking
315
optimal range of the trait nught have been of evolutionary advantage Of course, this would have tended to nanow the vanation in the trait But if the trait were a basis for assortative mating (mate choice based on similanty of some charactenstic) and based on poly genetic inhentance, the assortative mating would cause an increase in genetic vanance (Wilson, 1975) that could offset any disadvantage in the extreme manifestations of the trait Finally, there is the possibility that the trait is an incidental by-product of genetic variance that exists for some other reason and has never been strictly functional or adaptive (Buss, 1990) This kind of sociobiological speculation is interesting but largely post hoc Although It descnbes a possible source of selection for the trait m evolutionary history its relevance to current adaptation in the complex societies of today is questionable However, the theory does suggest that we might find hentable biological markers for the trait in currently extant organisms Sensation seeking has been shown to have relatively high hentability for a personality trait (Fulker, Eysenck, & Zuckennan, 1980) There is a high degree of assortative mating for the trait (Farley & Davis, 1977, Farley & Mueller, 1978), and the degree of congruence of the trait in marital partners is related to their mantal adjustment (Ficher, Zuckerman, & Neeb, 1981, Ficher, Zuckerman, & Steinberg, 1988) Sensation seeking has been related to engagement m a variety of nsky activities and to the extent and variety of heterosexual expenence (Zuckerman, 1979, Zuckerman, Tushup, & Finner, 1976) What I suggest is that certain psychophysiological mechanisms, that are themselves strongly hentable, may provide biological markers for Schneirla's A and W tendencies in humans and constitute part of the biological basis for the sensation-seekmg trait In one sense most of this research is correlational and cannot establish the etiological role of the psychophysiological trait m the psychological one Both may be regarded as functions of some common central mechanism What IS vaned in most of these expenments are the stimulus factors of intensity, novelty, and meaning Developmental studies suggest that the mteraction of temperament with reactivity to these stimulus factors appears early in life before much socialization has taken place Thomas and Chess (1977) use "Approach or Withdrawal" as one of their nine categories of temperament m infancy The dimension is defined as "the nature of the mitial response to a stimulus, be it a new food, new toy, or new person" (p 21) Assessments of this dimension of temperament at ages 3 and 4 i^edicted adult temperament, although the correlations were low (Thomas & Ctess, 1986) Kagan, Reznick, and Smdman (1988) report that high and stable
316
Zuckerman
heart rates and heart-rate acceleration to novel or cognitive stimuli from 21 months of age and older were significantly related to inhibited versus uninhibited behavior at 5 5 and 7 5 years of age Heart-rate patterns were reliable from 21 months to 7 5 years Pupillary dilation, another index of sympathetic activity, was also related to the trait of inhibition versus lmpulsivity In this article, I will review psychophysiological pattems of response to stimulus vanations in novelty, intensity, and meamng in high and low sensation seekers usmg three types of physiological response electrodermal and heart-rate responses and cortical evoked potentials Although tonic levels of arousal have played a major role in Eysenck's (1967) theory of Extraversion, we have found that specific kinds of arousability rather than general arousal are more important for the trait of sensation seeking While the concept of general arousal or arousability has been useful for theory building, the facts suggest that psychophysiological systems show individual response and stimulus-specific pattems so that it is nearly impossible tofinda pattem of general arousal applicable to all or most persons (Zuckerman, 1987a, Zuckerman & Como, 1983) For this reason, I will discuss the three psychophysiological systems separately and end with an attempt to interpret the results for all three in terms of pattems of adaptation specific to high and low sensation seekers
Sensation Seeking Scales (SSS) The SSS has been used as the standard test instrument for defining the trait of sensation seeking The initial version of the scale (SSS II, Zuckerman, Kolin, Pnce, & Zoob, 1964) contained only a general scale, derived from an initial factor analysis, with items expressing a desire to engage in activities providing excitement, nsk, and novelty or a preference for stimuh and people with these characteristics Subsequent factor analyses (Zuckerman, 1971), including more items, yielded four subscales (a) Thnll and Adventure Seeking, or the desire to engage in nsky physical activities or sports providmg unusual sensations, (b) Expenence Seeking, or the desire to seek new experience through the nund and senses and through an unconventional life-style and travel, (c) Disinhibition, or the seeking of sensation through other people or partying, social drinking, and sex, and (d) Boredom Susceptibility, or an aversion for unchanging or unstimulating environments or persons The most widely used current form of the SSS (Form V, Zuckerman,
Psychophysiology of Sensation Seeking
317
S B G Eysenck, & H J Eysenck [1978]), based on further factor analyses in England, is a shortened form of Form IV, using the most consistently loading items on the factors It also has a total score based on the sum of the four subscales The forms of the SSS have been translated into many languages and factor analyses in several countnes have essentially confirmed the four factors, although some items have shifted from one factor to another Onenting, Defense, a n d Startle Reflexes In discussing the psychophysiological responses to stimuli I will be making distinctions between three types of reaction orienting reflex, defensive reflex, and startle reflex The distinction between the first two, as elucidated by Sokolov (1963) and Graham (1979), involves the difference between responses that enhance sensitivity to external stimuli (onenting reflex) and those that reduce sensitivity (defensive reflex) Others have suggested that the defensive reflex, typically elicited by high intensities of stimulation, represents preparation for physical activity The startle reflex seems to represent an "interrupt" system m response to strong and unanticipated stimuli It is difficult to distinguish the three types of responses, except by reference to stimulus factors in uniphasic measures like skin resistance or conductance changes However, Graham (1979) has descnbed different charactenstics for defining the reflexes in heart-rate responses to stimuh The startle reflex is a short latency increase in heart rate, the defensive reflex is a long latency heart-rate increase, and the onenting reflex is a prolonged (2to 4-s) heart-rate decrease The relative strength of these types of responses could represent an important biological marker for personality differences Electrodennal Reactivity Three aspects of electrodermal reactivity will be discussed The tonic level of activity, or skm conductance level (SCL), reflects the electrodermal arousal just before or dunng the expenmental situation The phasic level, defined by the skin conductance response (SCR) measure, IS the amplitude of response to a given stimulus When the same stimulus IS presented a number of times m succession, one usually sees tiie strongest response to the first presentation and a diminished response with each subsequent presentation until there is no measur-
318
Zuckennan
able response This process is called habituation and may be measured m terms of tnals to extinction or slope of the regression line of response amplitude on tnals These measures are listed in Table 1 for nine expenments m eight studies Differences in tonic electrodermal arousal (SCL) between high and low sensation seekers have seldom been found, and when they do occur they are specific to certam conditions or subscales of the SSS In the studies by Smith, Perlstem, Davidson, and Michael (1986) and Stelmack, Plouffe, and Falkenberg (1983) high sensation seekers were more aroused (higher SCL) dunng conditions when words were presented as stimuli than dunng other stimulus conditions Nothing m the theory of sensation seeking explains this kmd of arousal specific to semantic stimuli Cox (1977) showed that high sensation seekers did not differ from lows at the beginning of a 70-mm penod of isolation m relatively depnved stimulus conditions, but the highs were lower in SCL at the end of the penod as a consequence of dropping in arousal, while the lows stayed the same over the penod This makes more sense in terms of the ongmal theory of sensation seeking (Zuckerman, 1969) that suggested stronger cortical inhibitory systems in highs However, an earlier study of electrodermal response to sensory depnvation (Zuckerman et al , 1966) did not yield differences between high and low sensation seekers, although the highs did become more restless m confinement conditions as reflected m body movements In the Robinson and Zahn (1983) study the highs on the Dismhibition subscale of the SSS showed higher SCLs than the lows, but the difference was not found when the general SSS was used to define high and low groups Five of the eight studies (Feij, Orlebeke, Gazendam, & van Zuilen, 1985, Neary & Zuckerman, 1976, Robinson & Zahn, 1983, Smith et al , 1986, Stelmack et al , 1983) found some evidence that high sensation seekers gave a stronger SCR, or onenting reflex, to the first presentation of a visual or auditory stimulus in a senes Figure 1 shows the results of the first expenment by Neary and Zuckerman (1976) to 10 presentations of a simple visual stimulus (rectangle) followed immediately by 10 presentations of a new stimulus (abstract design) Tlie male high sensation seekers responded more strongly than the lows to the first presentations of both stimuh, but for second presentations they immediately dropped to the level of the lows and habituated at the same rate to subsequent stimuh In further studies if differences occurred, the highs usually responded
Psychophysiology of Sensation Seeking
319
more than the lows when the stimulus was novel, but they responded at the same level as lows to second and subsequent presentations The exception was the study by Smith et al (1986) in which the stimuli withm a class were vaned and had content of specific interest to high sensation seekers The evidence from Stelmack et al (1983) is problematical for the sensation seekmg-electrodermal orienting reflex relationship since It was in opposite directions for two classes of visual stimuli, and the positive relationship with the word stimuli was not significant after controlling the SCR for SCL Three studies (Cox, 1977, Ridgeway & Hare, 1981, Zuckerman, Simons, & Como, 1988) did not support a sensation seeking-onentmg reflex relationship Even in the studies where there was a relationship, it was weak (r = 28 m Feij et al [1985], and 26 in Stelmack et al [ 1983]) More robust results were obtained in the Smith et al (1986) study in the form of highly significant interactions, and sometimes main effects, of sensation seeking and stimulus content The onenting reflex is an index of interest or focused attention on a particular stimulus In this case the stimulus meaning had positive value for high sensation seekers since it depicted activities or objects they value Based on studies of animals (mostly rodents) Gray (1973, 1982) has linked the orienting reflex to novel stimuh with anxiety, while I have suggested that the onenting reflex in humans is more often related to positive interest and arousal (Zuckerman, 1982, 1984a) In some of these studies the investigators examined the interaction of sensation seeking with trait and/or state anxiety in electrodermal responsivity Neary and Zuckerman (1976) selected subjects high or low on the four combinations of sensation seeking and trait anxiety While trait anxiety had no effect on electrodermal response, either alone or m interaction with sensation seeking, a state anxiety scale given just before the expenment began was related to response to both novel (first presentations) auditory sUmuh, and one ofthe two novel visual stimuh State anxiety was not related to sensation seeking so the effects of both were independent Subjects reporting high state anxiety gave weaker SCRs to the novel stimuh than those low m anxiety just pnor to the expenment Robmson and Zahn (1983) used the state anxiety scale from the State Trait Anxiety Inventory (Spielberger, Gorsuch, & Lushene, 1970) along with the SSS in selecting subjects They found significant interactions between anxiety and sensation seeking with low anxietyhigh sensatKjn-seekmg subjects manifesting the highest amplitudes of response to novel tones and fastest latencies, and the high anxiety-
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