TONIC
PHYSIOLOGICAL PRESENTATIONS JOHN
RESPONSES TO REPEATED OF PHOBIC STIMULI* F. CONNOLLY+
Laboratory of Neuro-Psychophysiology, Charing Cross Hospital, Fulham Palace Road, London W6 8RF. England (Received 21 June 1978) Summary-Qu~tionnaire. electrode~a~ and cardiac responses to phobic and neutral stimuli were assessed both within and across three daily test sessions. Each session consisted of 5 phobic and 5 neutral trials. Questionnaire responses in the first session showed some initial sensitization followed by habituation across the rest of the sessions. Cardiac response patterns differentiated phobic and neutral stimuli in the first two sessions. Electrodermal spontaneous fluctuation levels and habituation patterns differentiated the two stimulus types. Skin conductance levels showed sensitization across phobic trials and habituated across sessions. but showed habituation or asymptotic response levels to the neutral stimulus. The experiment rarses methodological points suggesting that conflicting and unexpected rest&s in the fiterature may be due to the use of phasic instead of tonic physiological responses and the use of stimuli which are not subject-specific. Results are also discussed in relation to proposals that psychiatric patients are those who are unable to cope with repeated life stresses.
INTRODUCTION
There are several reasons for determining whether habituation to complex emotional stimuli is similar to physiological habituation to neutral stimuli. Firstly, theories of anxiety such as Wolpe’s (1958) hypothesize different patterns of physiological responses to emotional and ‘neutral’ stimuli. Secondly, it has been suggested that habituation mechanisms operate in behaviour therapies such as systematic desensitization. which typically use complex stimuli (Lader, Gelder and Marks, 1967) and flooding (Watson. Gaind and Marks, 1972). Thirdly, it has been proposed that some people who develop psychiatric disorders due to life crises (Brown and Birley, 1968; Paykel, Myers. Diemelt. Klerman, Lindenthal and Peppers, 1969) may be unable to adapt or habituate to repeated stresses in life (Maguire, Maclean and Aitken, 1973). It is often assumed that habituation to complex emotional stimuli is different from habituation to neutral stimuli. Several lines of evidence make such an assumption questionable. Results of experiments on physiological responses to emotional stimuli have been contradictory, and unexpected. For example, skin conductance levels have been found to habituate (Averill. Malmstrom, Koriat and Lazarus, 1972) and sensitize (Maguire er al., 1973) to repeated presentations of a stressful film. Both studies found no difference between cardiac responses to emotional and neutral stimuli. These studies-like most others on this subject-make unjustified assumptions. Firstly, the use of films showing industrial accidents and circumcision rites (Averill CI al., 1972: Lazarus. Opton. Nomikos and Rankin; 1965; Lazarus, Speisman, Mordkoff and Davison. 1962; Maguire ef al., 1973) are more likely to evoke feelings such as disgust than emotions experienced by people during life stresses (e.g. anxiety). Secondly, it is inevitable that some people will find a film less stressful than others. For example, Hare (1972) found that only some subjects responded to pictures of mutilated bodies with cardiovascular patterns typical of a defensive response. Thirdly, most of these experiments study phasic responses where tonic measures would be of more direct importance to therapeutic techniques and theories of psychiatric illness. It is stress-related, maladaptive tonic responses which are related to psychosomatic disorders and possibly psychiatric illness. The notion that inability to habituate to life stresses may lead to psychiatric * This work was conducted at the Department of Psychology, institute of Psychiatry, London, England. The advice of Dr. 1. Martin is gratefully acknowledged. t N. W. Thames Regional Health Authority Fellow. 189
190
JOHN F. CONNOLLY
illness, while intuitively appealing, is difficult to evaluate because the few studies of habituation to complex emotional stimuli have produced conflicting results, have often assumed that all subjects would be similarly affected by the stimuli. and have frequently chosen to study phasic responses. The purpose of the present experiment was to study tonic physiological and psychological responses to phobic stimuli. The stimuli (tape recorded scene descriptions) were individualized for each subject in order to induce maximum stress and were designed to evoke emotions similar to stressful life situations.
METHODS Subjects
Thirty normal male Caucasian students and staff from a Medical School, who ranged in age from 19 to 30 years were tested. Subjects were interviewed several days before the experiment to determine an appropriate topic for their phobic stimulus. Only those who were able to name one object or situation, contemplation of which brought discomfort and was described as fear-provoking, were used. E.uperintental design
The experiment consisted of three SO-min sessions each composed of 5 phobic trials (4 min each), 5 neutral trials (4 min each). and 5 rating periods in which subjects completed a stress scale (2 min each). The trial sequence of phobic. rating period, and neutral was repeated 5 times to make a session. Subjects participated in one session per 24 h ( ~2 h) on three consecutive days. Stilllufi
All phobic and neutral stimuli were presented on tape recordings. The phobic stimulus consisted of a description of a scene or situation in which the subject was confronted by the object of his fear. These stimuli were composed in a manner identical to that used by clinicians for the therapeutic procedure of flooding. The neutral stimulus consisted of a description of a walk in the country. All stimuli were presented in a monotonous voice. Procedure
Subjects were seated in a darkened, sound-attenuated, shielded room with all recording apparatus kept in an adjoining room. The subject was familiarized with the stress scale (which was completed after each phobic trial) and was informed that tape recordings involving aspects of what had been discussed at the interview plus a description of a walk in the country would be presented. Subjects were paid and debriefed after the last session. Apparatus
The experiment was conducted on-line with a LINC-8 computer. Information (electrodermal, cardiac, and stimulus markers} were stored on magnetic tape and subsequently analysed with automatic scoring methods (Martin, Levey and Slubicka, 1975). Skin resistance (SR) was recorded on equipment built to the specifications of Venables and Martin (1967, model bf ) and used a constant current of 10 pA/cm2. Ag-AgCl electrodes (surface diameter was l.Ocm) and double stick 0 rings (diameter was l.lOcm) were attached to the medial phalanx of the 1st and 2nd fingers of the left hand. Heart period was recorded using a reflected photoplethysmograph (Sanei) over the medial phalanx of the small finger of the left hand. Dependent variables Ps~c~lo~agical. Responses to the phobic stimuli were measured using a stress scale with questions concerned with feelings of fear and anxiety, the ability to visualize the
Tonic physiological responses to repeated presentations of phobic stimuli
191
Table 1 (a) Session 1 @#
Univariate F
, Linear Quadratic 2 Linear Quadratic
1.24 I .24 1.24 1.24
9.53t 19.703 25.20f 17.35;
3 Quadratic Linear 4 Linear Quadratic
I .24 1.24
I .24
3;&
PHYSIOLOGICAL PRESENTATIONS JOHN
RESPONSES TO REPEATED OF PHOBIC STIMULI* F. CONNOLLY+
Laboratory of Neuro-Psychophysiology, Charing Cross Hospital, Fulham Palace Road, London W6 8RF. England (Received 21 June 1978) Summary-Qu~tionnaire. electrode~a~ and cardiac responses to phobic and neutral stimuli were assessed both within and across three daily test sessions. Each session consisted of 5 phobic and 5 neutral trials. Questionnaire responses in the first session showed some initial sensitization followed by habituation across the rest of the sessions. Cardiac response patterns differentiated phobic and neutral stimuli in the first two sessions. Electrodermal spontaneous fluctuation levels and habituation patterns differentiated the two stimulus types. Skin conductance levels showed sensitization across phobic trials and habituated across sessions. but showed habituation or asymptotic response levels to the neutral stimulus. The experiment rarses methodological points suggesting that conflicting and unexpected rest&s in the fiterature may be due to the use of phasic instead of tonic physiological responses and the use of stimuli which are not subject-specific. Results are also discussed in relation to proposals that psychiatric patients are those who are unable to cope with repeated life stresses.
INTRODUCTION
There are several reasons for determining whether habituation to complex emotional stimuli is similar to physiological habituation to neutral stimuli. Firstly, theories of anxiety such as Wolpe’s (1958) hypothesize different patterns of physiological responses to emotional and ‘neutral’ stimuli. Secondly, it has been suggested that habituation mechanisms operate in behaviour therapies such as systematic desensitization. which typically use complex stimuli (Lader, Gelder and Marks, 1967) and flooding (Watson. Gaind and Marks, 1972). Thirdly, it has been proposed that some people who develop psychiatric disorders due to life crises (Brown and Birley, 1968; Paykel, Myers. Diemelt. Klerman, Lindenthal and Peppers, 1969) may be unable to adapt or habituate to repeated stresses in life (Maguire, Maclean and Aitken, 1973). It is often assumed that habituation to complex emotional stimuli is different from habituation to neutral stimuli. Several lines of evidence make such an assumption questionable. Results of experiments on physiological responses to emotional stimuli have been contradictory, and unexpected. For example, skin conductance levels have been found to habituate (Averill. Malmstrom, Koriat and Lazarus, 1972) and sensitize (Maguire er al., 1973) to repeated presentations of a stressful film. Both studies found no difference between cardiac responses to emotional and neutral stimuli. These studies-like most others on this subject-make unjustified assumptions. Firstly, the use of films showing industrial accidents and circumcision rites (Averill CI al., 1972: Lazarus. Opton. Nomikos and Rankin; 1965; Lazarus, Speisman, Mordkoff and Davison. 1962; Maguire ef al., 1973) are more likely to evoke feelings such as disgust than emotions experienced by people during life stresses (e.g. anxiety). Secondly, it is inevitable that some people will find a film less stressful than others. For example, Hare (1972) found that only some subjects responded to pictures of mutilated bodies with cardiovascular patterns typical of a defensive response. Thirdly, most of these experiments study phasic responses where tonic measures would be of more direct importance to therapeutic techniques and theories of psychiatric illness. It is stress-related, maladaptive tonic responses which are related to psychosomatic disorders and possibly psychiatric illness. The notion that inability to habituate to life stresses may lead to psychiatric * This work was conducted at the Department of Psychology, institute of Psychiatry, London, England. The advice of Dr. 1. Martin is gratefully acknowledged. t N. W. Thames Regional Health Authority Fellow. 189
190
JOHN F. CONNOLLY
illness, while intuitively appealing, is difficult to evaluate because the few studies of habituation to complex emotional stimuli have produced conflicting results, have often assumed that all subjects would be similarly affected by the stimuli. and have frequently chosen to study phasic responses. The purpose of the present experiment was to study tonic physiological and psychological responses to phobic stimuli. The stimuli (tape recorded scene descriptions) were individualized for each subject in order to induce maximum stress and were designed to evoke emotions similar to stressful life situations.
METHODS Subjects
Thirty normal male Caucasian students and staff from a Medical School, who ranged in age from 19 to 30 years were tested. Subjects were interviewed several days before the experiment to determine an appropriate topic for their phobic stimulus. Only those who were able to name one object or situation, contemplation of which brought discomfort and was described as fear-provoking, were used. E.uperintental design
The experiment consisted of three SO-min sessions each composed of 5 phobic trials (4 min each), 5 neutral trials (4 min each). and 5 rating periods in which subjects completed a stress scale (2 min each). The trial sequence of phobic. rating period, and neutral was repeated 5 times to make a session. Subjects participated in one session per 24 h ( ~2 h) on three consecutive days. Stilllufi
All phobic and neutral stimuli were presented on tape recordings. The phobic stimulus consisted of a description of a scene or situation in which the subject was confronted by the object of his fear. These stimuli were composed in a manner identical to that used by clinicians for the therapeutic procedure of flooding. The neutral stimulus consisted of a description of a walk in the country. All stimuli were presented in a monotonous voice. Procedure
Subjects were seated in a darkened, sound-attenuated, shielded room with all recording apparatus kept in an adjoining room. The subject was familiarized with the stress scale (which was completed after each phobic trial) and was informed that tape recordings involving aspects of what had been discussed at the interview plus a description of a walk in the country would be presented. Subjects were paid and debriefed after the last session. Apparatus
The experiment was conducted on-line with a LINC-8 computer. Information (electrodermal, cardiac, and stimulus markers} were stored on magnetic tape and subsequently analysed with automatic scoring methods (Martin, Levey and Slubicka, 1975). Skin resistance (SR) was recorded on equipment built to the specifications of Venables and Martin (1967, model bf ) and used a constant current of 10 pA/cm2. Ag-AgCl electrodes (surface diameter was l.Ocm) and double stick 0 rings (diameter was l.lOcm) were attached to the medial phalanx of the 1st and 2nd fingers of the left hand. Heart period was recorded using a reflected photoplethysmograph (Sanei) over the medial phalanx of the small finger of the left hand. Dependent variables Ps~c~lo~agical. Responses to the phobic stimuli were measured using a stress scale with questions concerned with feelings of fear and anxiety, the ability to visualize the
Tonic physiological responses to repeated presentations of phobic stimuli
191
Table 1 (a) Session 1 @#
Univariate F
, Linear Quadratic 2 Linear Quadratic
1.24 I .24 1.24 1.24
9.53t 19.703 25.20f 17.35;
3 Quadratic Linear 4 Linear Quadratic
I .24 1.24
I .24
3;&
