- Email: [email protected]
Reactivity and response to pain
Perso,, :nd:rrd DI# Vol -, No 6. pp 90'-909.1986 Printed :n Great Bntaln
Reactivity DEBOR~ Deparrment
of Psychology.
and
response
L. DUBREUIL and
to pain
P,~L’L &I. KOHN
York L;nirersir,v, Dorwxiew. (Rewired
I5 Ocrober
Onlario.
,Lf_?J IPd Cumtk~
198~7
and female volunteers (IV = 144) answered the Reactivtty Scale (RS) and underaent testing for their perceived intensity and tolerance for finger-pressure pain. Half the Ss were randoml) assigned to a low-intensity treatment (I 150 g) and half to a high-intensity treatment (2300 g). Pain was rated at 30 and 60 sec., and Ss were asked to endure it as long as possible up to 5 min. The major findings were as follows: (I) women outscored men on reactivity; (2) the three pain measures intercorrelated highly: (3) high-intensity stimulation produced higher pain ratings and shorter tolerance than did low-tntensity stimulation; (4) men gave lower intensity ratings than women and tolerated the pain longer; (5) reactivity related positively to judged pain at 30 and 60sec. and negatively to pain tolerance; (6) there were no signtticant interaction effects among stimulus intensity, sex and reactivity for any pain measure: (7) the variance in the pain measures accounted for by stimulus intensity, sex and reactivity ranged from 76 to 32%. The implications were briefly discussed for the validity of the RS and factors explaining responses to experimentally-induced pain.
Summary-&tale
INTRODUCTION The concept of reactivity or ‘strength of the nervous system’ theoretically encompasses high sensitivity to weak stimulation. low ‘functional endurance’ or ability to cope with strong stimulation, low preferred level of stimulus intensity and high distractibility. Recently, Kohn (1985) developed a 24-item Likert-scaled measure of this construct. the Reactivity Sslile (RS). This measure showed T-reliabilities of 0.83. 0.79 and 0.73 in three independent samples (with IVS of 231. 212 and 60. respectively). Evidence for the test’s convergent validity came from predictable negative correlations with conceptually related but opposttely keyed measures, notably the Eysenck Personality Inventory’s (EPI) Extraversion (E) subscale (Eysenck and Eysenck. 1968), reducing on Vando’s (1970, 1974) Reducer-Augmenter Scale (R.4S). strength of excitation from the Strelau (1972) Temperament Inventory (STI) and the Gen(era1) subscale of the Sensation Seeking Scale, Form IV (SSS; Zuckerman. 197 I). Support for the RS’s discriminant validity came from its nonsignificant and very lo&vcorrelation with the conceptually unrelated Desire-for-novelty Scale (DFNS; Pearson, 1970). a measure of boredom and desire for change. A desirable source of support for the validity of the RS would be the demonstration of a predictable relattonship to a conceptually relevant hehacioural measure. One such measure which has already been related to extraversion (Barnes, 1975) and the RAS (Vando. 1970, 1974). both of which correlate appropriately with the RS. is pain tolerance. .4ccordingly, the present study examines the relationships of reactivity to the tolerance and perceived intensity of two experimentally induced levels of pain. This study’s design allows us to evaluate not only the main effects of objective stimulus intensity, measured reactivity and sex. but also their interactions.
METHOD The Ss were 72 male and 72 female undergraduates who had volunteered to participate in an experiment on ‘pain perception’ in return for a S5.00 payment. Before undergoing the testing for perceived intensity and tolerance for pain, Ss responded to the RS. Painful stimulation was administered via pressure to the index finger of the dominant hand, using Fiorgtone and Barber’s (1971) strain gauge stimulator. Two different weights were used, I I 5Og (low intensity) and 23OOg (high intensity), as previous research had shown these weights to be painful but discriminatively different (Spanos, Voorneveld and Gwynn, 1984). Ha!i the Ss of each sex underwent testing with one weight, and half with the other weight. Assignment to treatments was random. Subjects were asked to endure the stimulus for at least I min and as long thereafter as they could (up to a maximum of 5 min). Judgments of pain intensity were solicited after 30 and 60 set of stimulation. These were made on a predefined I l-point scale where 0 represented ‘no pain’, 5. ‘moderate pain’ and IO. ‘severe pain’. Thus, there were three dependent variables: judged pain at 30 and 60 set of stimulation, and pain tolerance or total time. up to 5 min. that a .S voluntarily continued to endure the pain.
RESULTS The z-reliability of the RS was 0.80 in the present sample. This is both adequate and in line with previous values (Kohn. 19S5). \Vomen (,?’ = 75.03. SD = 12.31). on average, outscored men (,Y = 69.55. SD = 12.20); ![I421 = 2.54. P < 0.02. Intercorrelations among stimulus intensity, sex, reactivity, rated pain at 30 and 60sec. and pain tolerance in seconds appear in Table I. Judged pain at 30 and 60 set correlated highly (r[l42] = 0.87. P = c 0.01); predictably, however, pain was consistently judged as more intense at 60 set than at 30 set (I [I431 = 19.83. P < 0.001). Both the 30 and 60 set ratings correlated substantially with pain tolerance (r = -0.61 and -0.64, respectively). 907
0) (2, (3) (‘I (51 (6)
The low and nonsignificant correlation between stimulus intensity and reactivtty attest to the success of random asstgnment. Stimulus intensity correlated predictably, If rather modestly. with both pLun ratings and with pain toleranie The correlations of sex with the three pain measures were also signilicant and of comparable magnitude. with men giving lower pain ratings and showing greater pain tolerance than women on average. Finally, reactivity correlated significantly. if modestly. with rated pain at 30 and 60 sec. and with pain tolerance. High reactives tended to rate pain as more Intense at both 30 and 60s~. and to endure it less protractedly than did low reacttves. Stepwise multiple regressions with hierarchical entry were computed with rated pain at 30 sec. rated pain at 60 set and pain tolerance as the criterion vartables. Sttmulus intensity, sex and reactivtty were entered first as predictors, then their pairwise interactions, and finally the triple interaction. The results are summarized in Table 2. First, no interactions proved to be significant predictors of any criterion measure. However. stimulus intensity. sex and reactivity were all significant predictors for all three criteria, provided that one slightly relaxed the usual 0.05 y-level for reactivity as a predictor of rated pain at 30 sec. (There are tvvo good reasons for doing so: the high intercorrelattons among the pain measures, and the significant impact of reactivity on rated pain at 60 set and on pain tolerance.) Sex and stimulus intensity accounted for roughly comparable proportions of variance tn all three cases. iclth reactivity showing considerably less impact.
DISCUSSIOS The finding that the RS predicts both judged intensity and tolerance for patn supports its construct validity. While it might seem that ‘-5% of the variance in the pain measures is not dramatic. it should be noted that stimulus intensity accounted for only I I-14% of the variance. In this light, Z-5% of the variance seems ratrly respectable. Clearly, given the values of R’ which range from 0.26 to 0.32, a lot of variance is not accounted for. Possibly, such unmeasured factors as 1975) play an important role. the need for social approval (Crowns and Marlow. 1961: hftlham and Jacobson, It is notable that the interaction between reactivity and stimulus intensity. like all the other interacttons. was nonsignificant. This indicates that, at least within the modest range of stimulus intensity sampled. the contribution or measured reactivity to the reported experience and demonstrated tolerance for pain is fairly uniform. ~cX_nou,/~dgements-This project was supported by a Predoctoral Student Ministry of Health. and completed while the second author held Research 451-85-076-t from the Social Sciences and Humanities Research Council of the helpful comments of Dr Norman S. End& on an earlier draft of thts Requests for reprints should be addressed to P. M Kohn.
*Award to the first author from the Ontarto Grant So. 410-83-1270 and Leave Grant NO. Canada. The authors gratefully acknowledge manuscript
REFERESCES Barnes G. E. (1975) Extraversion and pain. Br. J. sot. clin. Ps)chol. Crowne D. P. and Marlowe D. (196-t) The rlppro~ol .Lfolice. Wiley,
14 303-308 New York.
VOTE.5
ASD
SHORTER CO~t~IUSICATIOYS
909
Eysenck H. J. and Eysenck S. 8. G. (1968) .Monual bf rhe Ewvcii Perronaiir~ fnrenror~. EdlTS. San Diego, &Iii. Fiorgtone A. and Barber T. X. (1971) A strain gauge pain stimulator. Ps~choph~sioiop~ 8, 102-106. Kohn P. Xl. (1985) Sensation seeking. augmentmg-reducing and strength of the ner\ous system. In .Lloiwuiwn. Enrorion anti Personalr~y: Proceedrngs oJ‘ the XXIII Imernarional Congress of Psxcholq! (Edtted by Spews J T. and lzard C.). Sorth Holland-Elsevier. Amsterdam. Milham J. and Jacobson L. (1978) The need for approval. In Dmensions o/ Personnli~y (Edited by London H. and Exner J. E.). Wiley. New York. Pearson P. H. (1970) Relationshtps between global and specified measures of novelty seeking. J. cansuir. clln. Psxchoi. 3, 199-204. Spanos $. P.. Voorneveld P. and Gwynn M. (1983) The mediating effects of expectation on hypnotic and nonhypnotic pain reduction. Unpublished manuscript, Carleton Univ. Ottawa. Canada. Strelau J. (1972) A diagnosis of temperament by non-experimental techniques. Pal. PsFchoi. Bull. 3, 97-105. Strelau J. (1983) ‘Iemperamen~, Personnliry, Activity. Academic Press, New York. Vando A. (1970) A personality dimension related to pain tolerance. Doctoral Dissertation, Columbia Univ. New York (1969). Dissert. Abrrr. Int. 31, 2292E22938. (University Microfilms No. 7&18,865.) Vando A. (1974) The development of the R-A Scale; a paper-and-pencil measure of pain tolerance. Person. WC. Psychol. Bull. 1, 28-29. Zuckerman M. (1971) Dimensions of sensation seeking. J. consult. c/in. Psycho/. 36, 45-52.
Reactivity DEBOR~ Deparrment
of Psychology.
and
response
L. DUBREUIL and
to pain
P,~L’L &I. KOHN
York L;nirersir,v, Dorwxiew. (Rewired
I5 Ocrober
Onlario.
,Lf_?J IPd Cumtk~
198~7
and female volunteers (IV = 144) answered the Reactivtty Scale (RS) and underaent testing for their perceived intensity and tolerance for finger-pressure pain. Half the Ss were randoml) assigned to a low-intensity treatment (I 150 g) and half to a high-intensity treatment (2300 g). Pain was rated at 30 and 60 sec., and Ss were asked to endure it as long as possible up to 5 min. The major findings were as follows: (I) women outscored men on reactivity; (2) the three pain measures intercorrelated highly: (3) high-intensity stimulation produced higher pain ratings and shorter tolerance than did low-tntensity stimulation; (4) men gave lower intensity ratings than women and tolerated the pain longer; (5) reactivity related positively to judged pain at 30 and 60sec. and negatively to pain tolerance; (6) there were no signtticant interaction effects among stimulus intensity, sex and reactivity for any pain measure: (7) the variance in the pain measures accounted for by stimulus intensity, sex and reactivity ranged from 76 to 32%. The implications were briefly discussed for the validity of the RS and factors explaining responses to experimentally-induced pain.
Summary-&tale
INTRODUCTION The concept of reactivity or ‘strength of the nervous system’ theoretically encompasses high sensitivity to weak stimulation. low ‘functional endurance’ or ability to cope with strong stimulation, low preferred level of stimulus intensity and high distractibility. Recently, Kohn (1985) developed a 24-item Likert-scaled measure of this construct. the Reactivity Sslile (RS). This measure showed T-reliabilities of 0.83. 0.79 and 0.73 in three independent samples (with IVS of 231. 212 and 60. respectively). Evidence for the test’s convergent validity came from predictable negative correlations with conceptually related but opposttely keyed measures, notably the Eysenck Personality Inventory’s (EPI) Extraversion (E) subscale (Eysenck and Eysenck. 1968), reducing on Vando’s (1970, 1974) Reducer-Augmenter Scale (R.4S). strength of excitation from the Strelau (1972) Temperament Inventory (STI) and the Gen(era1) subscale of the Sensation Seeking Scale, Form IV (SSS; Zuckerman. 197 I). Support for the RS’s discriminant validity came from its nonsignificant and very lo&vcorrelation with the conceptually unrelated Desire-for-novelty Scale (DFNS; Pearson, 1970). a measure of boredom and desire for change. A desirable source of support for the validity of the RS would be the demonstration of a predictable relattonship to a conceptually relevant hehacioural measure. One such measure which has already been related to extraversion (Barnes, 1975) and the RAS (Vando. 1970, 1974). both of which correlate appropriately with the RS. is pain tolerance. .4ccordingly, the present study examines the relationships of reactivity to the tolerance and perceived intensity of two experimentally induced levels of pain. This study’s design allows us to evaluate not only the main effects of objective stimulus intensity, measured reactivity and sex. but also their interactions.
METHOD The Ss were 72 male and 72 female undergraduates who had volunteered to participate in an experiment on ‘pain perception’ in return for a S5.00 payment. Before undergoing the testing for perceived intensity and tolerance for pain, Ss responded to the RS. Painful stimulation was administered via pressure to the index finger of the dominant hand, using Fiorgtone and Barber’s (1971) strain gauge stimulator. Two different weights were used, I I 5Og (low intensity) and 23OOg (high intensity), as previous research had shown these weights to be painful but discriminatively different (Spanos, Voorneveld and Gwynn, 1984). Ha!i the Ss of each sex underwent testing with one weight, and half with the other weight. Assignment to treatments was random. Subjects were asked to endure the stimulus for at least I min and as long thereafter as they could (up to a maximum of 5 min). Judgments of pain intensity were solicited after 30 and 60 set of stimulation. These were made on a predefined I l-point scale where 0 represented ‘no pain’, 5. ‘moderate pain’ and IO. ‘severe pain’. Thus, there were three dependent variables: judged pain at 30 and 60 set of stimulation, and pain tolerance or total time. up to 5 min. that a .S voluntarily continued to endure the pain.
RESULTS The z-reliability of the RS was 0.80 in the present sample. This is both adequate and in line with previous values (Kohn. 19S5). \Vomen (,?’ = 75.03. SD = 12.31). on average, outscored men (,Y = 69.55. SD = 12.20); ![I421 = 2.54. P < 0.02. Intercorrelations among stimulus intensity, sex, reactivity, rated pain at 30 and 60sec. and pain tolerance in seconds appear in Table I. Judged pain at 30 and 60 set correlated highly (r[l42] = 0.87. P = c 0.01); predictably, however, pain was consistently judged as more intense at 60 set than at 30 set (I [I431 = 19.83. P < 0.001). Both the 30 and 60 set ratings correlated substantially with pain tolerance (r = -0.61 and -0.64, respectively). 907
0) (2, (3) (‘I (51 (6)
The low and nonsignificant correlation between stimulus intensity and reactivtty attest to the success of random asstgnment. Stimulus intensity correlated predictably, If rather modestly. with both pLun ratings and with pain toleranie The correlations of sex with the three pain measures were also signilicant and of comparable magnitude. with men giving lower pain ratings and showing greater pain tolerance than women on average. Finally, reactivity correlated significantly. if modestly. with rated pain at 30 and 60 sec. and with pain tolerance. High reactives tended to rate pain as more Intense at both 30 and 60s~. and to endure it less protractedly than did low reacttves. Stepwise multiple regressions with hierarchical entry were computed with rated pain at 30 sec. rated pain at 60 set and pain tolerance as the criterion vartables. Sttmulus intensity, sex and reactivtty were entered first as predictors, then their pairwise interactions, and finally the triple interaction. The results are summarized in Table 2. First, no interactions proved to be significant predictors of any criterion measure. However. stimulus intensity. sex and reactivity were all significant predictors for all three criteria, provided that one slightly relaxed the usual 0.05 y-level for reactivity as a predictor of rated pain at 30 sec. (There are tvvo good reasons for doing so: the high intercorrelattons among the pain measures, and the significant impact of reactivity on rated pain at 60 set and on pain tolerance.) Sex and stimulus intensity accounted for roughly comparable proportions of variance tn all three cases. iclth reactivity showing considerably less impact.
DISCUSSIOS The finding that the RS predicts both judged intensity and tolerance for patn supports its construct validity. While it might seem that ‘-5% of the variance in the pain measures is not dramatic. it should be noted that stimulus intensity accounted for only I I-14% of the variance. In this light, Z-5% of the variance seems ratrly respectable. Clearly, given the values of R’ which range from 0.26 to 0.32, a lot of variance is not accounted for. Possibly, such unmeasured factors as 1975) play an important role. the need for social approval (Crowns and Marlow. 1961: hftlham and Jacobson, It is notable that the interaction between reactivity and stimulus intensity. like all the other interacttons. was nonsignificant. This indicates that, at least within the modest range of stimulus intensity sampled. the contribution or measured reactivity to the reported experience and demonstrated tolerance for pain is fairly uniform. ~cX_nou,/~dgements-This project was supported by a Predoctoral Student Ministry of Health. and completed while the second author held Research 451-85-076-t from the Social Sciences and Humanities Research Council of the helpful comments of Dr Norman S. End& on an earlier draft of thts Requests for reprints should be addressed to P. M Kohn.
*Award to the first author from the Ontarto Grant So. 410-83-1270 and Leave Grant NO. Canada. The authors gratefully acknowledge manuscript
REFERESCES Barnes G. E. (1975) Extraversion and pain. Br. J. sot. clin. Ps)chol. Crowne D. P. and Marlowe D. (196-t) The rlppro~ol .Lfolice. Wiley,
14 303-308 New York.
VOTE.5
ASD
SHORTER CO~t~IUSICATIOYS
909
Eysenck H. J. and Eysenck S. 8. G. (1968) .Monual bf rhe Ewvcii Perronaiir~ fnrenror~. EdlTS. San Diego, &Iii. Fiorgtone A. and Barber T. X. (1971) A strain gauge pain stimulator. Ps~choph~sioiop~ 8, 102-106. Kohn P. Xl. (1985) Sensation seeking. augmentmg-reducing and strength of the ner\ous system. In .Lloiwuiwn. Enrorion anti Personalr~y: Proceedrngs oJ‘ the XXIII Imernarional Congress of Psxcholq! (Edtted by Spews J T. and lzard C.). Sorth Holland-Elsevier. Amsterdam. Milham J. and Jacobson L. (1978) The need for approval. In Dmensions o/ Personnli~y (Edited by London H. and Exner J. E.). Wiley. New York. Pearson P. H. (1970) Relationshtps between global and specified measures of novelty seeking. J. cansuir. clln. Psxchoi. 3, 199-204. Spanos $. P.. Voorneveld P. and Gwynn M. (1983) The mediating effects of expectation on hypnotic and nonhypnotic pain reduction. Unpublished manuscript, Carleton Univ. Ottawa. Canada. Strelau J. (1972) A diagnosis of temperament by non-experimental techniques. Pal. PsFchoi. Bull. 3, 97-105. Strelau J. (1983) ‘Iemperamen~, Personnliry, Activity. Academic Press, New York. Vando A. (1970) A personality dimension related to pain tolerance. Doctoral Dissertation, Columbia Univ. New York (1969). Dissert. Abrrr. Int. 31, 2292E22938. (University Microfilms No. 7&18,865.) Vando A. (1974) The development of the R-A Scale; a paper-and-pencil measure of pain tolerance. Person. WC. Psychol. Bull. 1, 28-29. Zuckerman M. (1971) Dimensions of sensation seeking. J. consult. c/in. Psycho/. 36, 45-52.