Percepiual and Motor Skills, 1975,40, 283-288.
Perceptual and Motor Skills 1975
CONDITIONING CHANGES I N DIFFERENTIAL SKIN TEMPERATURE1 FRANCIS J. KEEFE Ohio Uniumsity Summory -8 male Ss were presented with visual and auditory analog feedback regarding the difference between forehead and finger temperarure. 4 Ss were lnsrructed to raise the temperature of their finger in comparison with the forehead, while a second group of 4 Ss was instructed to lower the temperature of their finger in comparison with the temperature of the forehead. After 12 15-min. training sessions all Ss were able to produce changes in differential skin temperature in the specified direction. Differential changes in skin temperature correlated highly with changes in absolute finger temperature. These results are discussed as relevant to the clinical application of skin temperarure control.
The recent application of operant conditioning techniques to the modi fication of autonomic responses has generated considerable interest both in laymen (Stoler, 1974) and scientists (Davidson & Krippner, 1972; Schwartz, 1973). Experiments using such techniques have demonstrated that humans can gain some degree of voluntary control over such "involuntary" functions as heart rate (Engel & Chism, 1967), blood pressure (Shapiro, Tursky, & Schwartz, 1970), and vasomotor responses (Christie & Kotses, 1973). Autonomic self-control likewise has stimulated keen interest among clinicians. The ability to control peripheral skin temperacure appears to be especially helpful in the treatment of certain vascular disorders. For example, Sargent, Green, and Walters ( 1973) found that pain associated with migraine headache was markedly reduced after 2 to 4 mo. of daily feedback training to increase hand, relative to midforehead, skin temperature. Case studies (Peper, 1972; Peper & Grossman, 1974) using similar differential hand-forehead feedback training have also reported successful treatment of patients suffering from Raynaud's disease. Recently, a number of investigations, conducted under more controlled laboratory conditions, have purported to demonstrate the conditioning of differential skin temperature changes of relatively large magnitude (McDonagh & McG i ~ i s 1973; , Roberts, Kewman, & Macdonald, 1973; Taub & Emurian, 1971, 1972). These studies, however, are open to criticism on several grounds. First, in each study biofeedback training has been used in conjunction with an instructional set, designed to induce skin temperature changes, e.g., autogenic phrases ( McDonagh & McGinnis, 1973), hypnotic suggestions (Roberts, et al., 1973), 'Requests for reprints should be sent to Francis J. Keefe, Psychology Dept., Ohio Universiry, Athens, Ohio 45701.
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or encouragement to use "thermal imagery" (Taub & Emurian, 1971,1372). The simultaneous use of such multiple treatment procedures makes it impossible to evaluate whether feedback or the specific instructional sets are responsible for the observed changes in skin temperature. Secondly, with che exception of Roberts, et al. (1973), no data have been presented on changes in absolute temperature of each skin site measured during differential temperature training. The present study attempted to meet the above criticisms. Subjects were given both feedback and response-specific instructions. The responsespecific instructions were simple and straightforward. They merely informed Ss of the response being monitored and the direction of temperature change desired. The purpose of the study was: ( a ) to investigate whether Ss could produce either increases in differential skin temperature (Increase group) or decreases in differential skin temperature (Decrease group), and ( b ) to investigate the relationship between over-all ch~ngesin differential skin temperature and changes in the absolute temperature of the finger.
METHOD Subjects Ss were eight male college students, ages 18 to 21 yr. enrolled in courses in introductory psychology. Apparatus Differential skin temperature was recorded on a Varian Model G-14 single channel recorder. Measurements of hand-forehead differential skin temperature were made using two Yellow Springs thermistors and a Biofeedback Technology Model BFT3Ol feedback thermometer in differential mode. One thermistor was positioned on the right index finger and the other was positioned on the midforehead. The output of the feedback thermometer was used to control continuous auditory and visual feedback delivered to Ss. The auditory feedback, presented through headphones, consisted of a soft tone which varied in pitch as a function of the difference between hand and forehead skin temperature. An increase in hand relative to forehead temperature resulted in an increase in tone frequency, while a decrease in hand relative to forehead temperature resulted in a decrease in tone frequency. The visual feedback consisted of a closed-circuit television picture of the center-set meter mounted on the feedback thermometer. A Panasonic Model W V 220P video camera was used to transmit the picture and the feedback was presented to S on a Magnavox 24-in. monitor. Changes in differential skin temperature were indicated on the meter as follows: an increase in hand relative to forehead temperature resulted in deflection of the meter needle from rhe center to the right, while a decrease in hand relative to forehead temperature resulted in deflection of the meter needle from the center to the left.
CONDITIONED CHANGE OF SKIN TEMPERATURE
285
Measurements of absolute temperature of the right index finger were recorded by E using the feedback thermometer in absolute mode. Pro cedwe Ss were randomly assigned in equal numbers to one of two groups: an Increase group, in which Ss were trained to produce increases in hand relative to forehead temperature, and a Decrease group in which decreases in hand relative to forehead temperature were conditioned. All Ss participated in 12 training sessions on 12 consecutive days. Each session consisted of a 5-min. rest followed by a 10-min. feedback period. At the start of a session each S was seated in a comfortable chair in a room maintained at 70°F. Thermistors were positioned on the right index finger and midforehead with surgical tape. Increase group Ss were instructed that their task was to raise the temperature OF the right hand relative to the temperature of the forehead during the feedback period. They were also informed that when they were successful the pitch of the feedback cone would increase and the needle on the feedback meter would move to the right. Decrease group Ss were told that their task was to lower the temperature of the hand relative to the temperature OF the forehead and that success in doing this would be indicated by a decrease in the pitch of the feedback tone and movement of the meter needle to the left. All Ss were instructed to refrain from irregular respiration and unnecessary movement. After reading the instructions, and placing the earphones on S, E entered an adjacent control room, and initiated the training session. During the 5-min. rest S was given no feedback. The first 2 min. of this period were used for equipment warmup and the last 3 min. were used as a baseline period during which measurements of differential skin temperature were recorded. At the end of the rest period an initial measurement of absolute temperature of the right finger was taken. The differential thermometer was then rebalanced so that the needle was positioned at a zero-center reading, and S was presented with a 10-min. feedback period during which both auditory and visual feedback were presented. At the end of the feedback period a second measurement of absolute finger temperature was taken.
RESULTS~ AND DISCUSSION Fig. 1 portrays the mean change in differential skin temperature of Ss in the Increase and in the Decrease group during the twelfth training session. Inspection clearly suggests that bidirectional changes in differential forehead-hand skin temperature were obtained as a result of feedback training. Ss in the Increase group showed an average increase in differential skin temperature of up Tour supplementary tables of more detailed results can be obtained by writing t o : Microfiche Publications, 440 Park Ave. S., New York, N. Y. 10016 for Document NAPS02451. Remit $1.50 for microfiche or $5.00 for photocopy.
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FIG. 1. Mean change i n differential temperature occurring during baseline and feedback periods of craining Session 12 for Increase and Decrease groups
to 1.9"F over the 10-min, feedback period, while Ss in the Decrease group showed an average decrease of up to l.S°F over this same period. Changes in Ss' differential temperature during the twelfth session were calculated at 1-min. intervals, and an analysis of variance was then computed for the Increase and Decrease groups. Increase and Decrease groups differed significantly ( F I , = ~ 46.88, p < .01). In addition, the interaction of Groups X Minutes of Feedback (F0,54 = 18.17, p < .01) was significant. Post hoc comparisons between the means for the two groups were made for Mins. 1, 3, 5,7, and 9 of the feedback period by means of Tukey's HSD statistic. The results of these comparisons indicated that there was no statistically significant difference between the performance of the Increase and Decrease groups after one minute of feedback, although significant differences between the two groups occurred after both 3, 5, 7, and 9 min. of feedback. To analyze variations in absolute skin temperature of the right finger over the feedback period, change scores were computed by subtracting the initial absolute skin temperature reading from the final reading. Over the 10-min. feedback period, Increase group Ss showed an average increase in absolute finger temperature of 1.7OF, whereas Decrease group Ss showed an average decrease of 1.2"F. Furthermore, changes in absolute finger temperature correlated highly ( r = .87, .01) with over-all changes in differential skin temperature. Thus, bidirectional changes in absolute finger temperature occurred concurrently with bidirectional changes in differential skin temperature.
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Perceptual and Motor Skills 1975
CONDITIONING CHANGES I N DIFFERENTIAL SKIN TEMPERATURE1 FRANCIS J. KEEFE Ohio Uniumsity Summory -8 male Ss were presented with visual and auditory analog feedback regarding the difference between forehead and finger temperarure. 4 Ss were lnsrructed to raise the temperature of their finger in comparison with the forehead, while a second group of 4 Ss was instructed to lower the temperature of their finger in comparison with the temperature of the forehead. After 12 15-min. training sessions all Ss were able to produce changes in differential skin temperature in the specified direction. Differential changes in skin temperature correlated highly with changes in absolute finger temperature. These results are discussed as relevant to the clinical application of skin temperarure control.
The recent application of operant conditioning techniques to the modi fication of autonomic responses has generated considerable interest both in laymen (Stoler, 1974) and scientists (Davidson & Krippner, 1972; Schwartz, 1973). Experiments using such techniques have demonstrated that humans can gain some degree of voluntary control over such "involuntary" functions as heart rate (Engel & Chism, 1967), blood pressure (Shapiro, Tursky, & Schwartz, 1970), and vasomotor responses (Christie & Kotses, 1973). Autonomic self-control likewise has stimulated keen interest among clinicians. The ability to control peripheral skin temperacure appears to be especially helpful in the treatment of certain vascular disorders. For example, Sargent, Green, and Walters ( 1973) found that pain associated with migraine headache was markedly reduced after 2 to 4 mo. of daily feedback training to increase hand, relative to midforehead, skin temperature. Case studies (Peper, 1972; Peper & Grossman, 1974) using similar differential hand-forehead feedback training have also reported successful treatment of patients suffering from Raynaud's disease. Recently, a number of investigations, conducted under more controlled laboratory conditions, have purported to demonstrate the conditioning of differential skin temperature changes of relatively large magnitude (McDonagh & McG i ~ i s 1973; , Roberts, Kewman, & Macdonald, 1973; Taub & Emurian, 1971, 1972). These studies, however, are open to criticism on several grounds. First, in each study biofeedback training has been used in conjunction with an instructional set, designed to induce skin temperature changes, e.g., autogenic phrases ( McDonagh & McGinnis, 1973), hypnotic suggestions (Roberts, et al., 1973), 'Requests for reprints should be sent to Francis J. Keefe, Psychology Dept., Ohio Universiry, Athens, Ohio 45701.
284
F. J. KEEFE
or encouragement to use "thermal imagery" (Taub & Emurian, 1971,1372). The simultaneous use of such multiple treatment procedures makes it impossible to evaluate whether feedback or the specific instructional sets are responsible for the observed changes in skin temperature. Secondly, with che exception of Roberts, et al. (1973), no data have been presented on changes in absolute temperature of each skin site measured during differential temperature training. The present study attempted to meet the above criticisms. Subjects were given both feedback and response-specific instructions. The responsespecific instructions were simple and straightforward. They merely informed Ss of the response being monitored and the direction of temperature change desired. The purpose of the study was: ( a ) to investigate whether Ss could produce either increases in differential skin temperature (Increase group) or decreases in differential skin temperature (Decrease group), and ( b ) to investigate the relationship between over-all ch~ngesin differential skin temperature and changes in the absolute temperature of the finger.
METHOD Subjects Ss were eight male college students, ages 18 to 21 yr. enrolled in courses in introductory psychology. Apparatus Differential skin temperature was recorded on a Varian Model G-14 single channel recorder. Measurements of hand-forehead differential skin temperature were made using two Yellow Springs thermistors and a Biofeedback Technology Model BFT3Ol feedback thermometer in differential mode. One thermistor was positioned on the right index finger and the other was positioned on the midforehead. The output of the feedback thermometer was used to control continuous auditory and visual feedback delivered to Ss. The auditory feedback, presented through headphones, consisted of a soft tone which varied in pitch as a function of the difference between hand and forehead skin temperature. An increase in hand relative to forehead temperature resulted in an increase in tone frequency, while a decrease in hand relative to forehead temperature resulted in a decrease in tone frequency. The visual feedback consisted of a closed-circuit television picture of the center-set meter mounted on the feedback thermometer. A Panasonic Model W V 220P video camera was used to transmit the picture and the feedback was presented to S on a Magnavox 24-in. monitor. Changes in differential skin temperature were indicated on the meter as follows: an increase in hand relative to forehead temperature resulted in deflection of the meter needle from rhe center to the right, while a decrease in hand relative to forehead temperature resulted in deflection of the meter needle from the center to the left.
CONDITIONED CHANGE OF SKIN TEMPERATURE
285
Measurements of absolute temperature of the right index finger were recorded by E using the feedback thermometer in absolute mode. Pro cedwe Ss were randomly assigned in equal numbers to one of two groups: an Increase group, in which Ss were trained to produce increases in hand relative to forehead temperature, and a Decrease group in which decreases in hand relative to forehead temperature were conditioned. All Ss participated in 12 training sessions on 12 consecutive days. Each session consisted of a 5-min. rest followed by a 10-min. feedback period. At the start of a session each S was seated in a comfortable chair in a room maintained at 70°F. Thermistors were positioned on the right index finger and midforehead with surgical tape. Increase group Ss were instructed that their task was to raise the temperature OF the right hand relative to the temperature of the forehead during the feedback period. They were also informed that when they were successful the pitch of the feedback cone would increase and the needle on the feedback meter would move to the right. Decrease group Ss were told that their task was to lower the temperature of the hand relative to the temperature OF the forehead and that success in doing this would be indicated by a decrease in the pitch of the feedback tone and movement of the meter needle to the left. All Ss were instructed to refrain from irregular respiration and unnecessary movement. After reading the instructions, and placing the earphones on S, E entered an adjacent control room, and initiated the training session. During the 5-min. rest S was given no feedback. The first 2 min. of this period were used for equipment warmup and the last 3 min. were used as a baseline period during which measurements of differential skin temperature were recorded. At the end of the rest period an initial measurement of absolute temperature of the right finger was taken. The differential thermometer was then rebalanced so that the needle was positioned at a zero-center reading, and S was presented with a 10-min. feedback period during which both auditory and visual feedback were presented. At the end of the feedback period a second measurement of absolute finger temperature was taken.
RESULTS~ AND DISCUSSION Fig. 1 portrays the mean change in differential skin temperature of Ss in the Increase and in the Decrease group during the twelfth training session. Inspection clearly suggests that bidirectional changes in differential forehead-hand skin temperature were obtained as a result of feedback training. Ss in the Increase group showed an average increase in differential skin temperature of up Tour supplementary tables of more detailed results can be obtained by writing t o : Microfiche Publications, 440 Park Ave. S., New York, N. Y. 10016 for Document NAPS02451. Remit $1.50 for microfiche or $5.00 for photocopy.
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FIG. 1. Mean change i n differential temperature occurring during baseline and feedback periods of craining Session 12 for Increase and Decrease groups
to 1.9"F over the 10-min, feedback period, while Ss in the Decrease group showed an average decrease of up to l.S°F over this same period. Changes in Ss' differential temperature during the twelfth session were calculated at 1-min. intervals, and an analysis of variance was then computed for the Increase and Decrease groups. Increase and Decrease groups differed significantly ( F I , = ~ 46.88, p < .01). In addition, the interaction of Groups X Minutes of Feedback (F0,54 = 18.17, p < .01) was significant. Post hoc comparisons between the means for the two groups were made for Mins. 1, 3, 5,7, and 9 of the feedback period by means of Tukey's HSD statistic. The results of these comparisons indicated that there was no statistically significant difference between the performance of the Increase and Decrease groups after one minute of feedback, although significant differences between the two groups occurred after both 3, 5, 7, and 9 min. of feedback. To analyze variations in absolute skin temperature of the right finger over the feedback period, change scores were computed by subtracting the initial absolute skin temperature reading from the final reading. Over the 10-min. feedback period, Increase group Ss showed an average increase in absolute finger temperature of 1.7OF, whereas Decrease group Ss showed an average decrease of 1.2"F. Furthermore, changes in absolute finger temperature correlated highly ( r = .87, .01) with over-all changes in differential skin temperature. Thus, bidirectional changes in absolute finger temperature occurred concurrently with bidirectional changes in differential skin temperature.
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