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Effects of attentional direction, age, and coping style on cold-pressor pain in children
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Behaviour Research and Therapy 44 (2006) 835–848 www.elsevier.com/locate/brat
Effects of attentional direction, age, and coping style on cold-pressor pain in children Tiina Piiraa,b,, Brett Hayesb, Belinda Goodenoughb,c, Carl L. von Baeyerd a
Pain Research Unit, Sydney Children’s Hospital, High Street, Randwick NSW 2031, Australia b School of Psychology, University of New South Wales, Sydney, Australia c Centre for Children’s Cancer & Blood Disorders, Sydney Children’s Hospital, Randwick, Australia d Departments of Psychology and Pediatrics, University of Saskatchewan, Saskatoon, Canada Received 12 January 2004; received in revised form 6 March 2005; accepted 6 March 2005
Abstract This study assessed the relative efficacy of two imagery-based attentional strategies for modifying pain experience in children. Children aged 7–14 years (n ¼ 120) were randomly assigned to one of three conditions: distraction, sensory-focussing or control (no imagery). The distraction condition prompted children to focus their attention externally; the sensory-focussing condition prompted the child to focus internally on physical sensations. Self-report measures of pain coping style preferences and imagery ability were completed. Children’s pain tolerance and perceptions of pain intensity were assessed using a 10 1C cold-pressor task. Results showed pain intensity ratings after 1 min were lower for both intervention conditions than for the controls. Younger children (7–9 years) showed higher pain tolerance in the distraction condition than in the sensory-focussing condition, whereas both interventions were equally effective for older children (10–14 years). Among older children, coping style interacted with the intervention type: in the sensory-focussing condition, pain tolerance was negatively associated with self-reported distraction-based coping style, whereas in the distraction condition this association was positive. The results are interpreted with reference to current models of attention. The implications for use of attentional strategies in helping children to cope with clinical pain are discussed. r 2005 Elsevier Ltd. All rights reserved. Keywords: Attention; Child; Cold-pressor; Coping; Distraction; Pain
Corresponding author. Pain Research Unit, Sydney Children’s Hospital, High Street, Randwick NSW 2031,
Australia. Tel.: +61 2 9382 1585; fax: +61 2 9382 7946. E-mail address: [email protected] (T. Piira). 0005-7967/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.brat.2005.03.013
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Introduction Instruction in attentional coping strategies, such as distraction, is often used in the clinical management of children’s acute pain. However, the mechanisms by which coping strategies may influence children’s pain outcomes are not well understood. Hence, it is not always clear which types of attentional strategies are likely to be most effective in pediatric pain. Two types of attentional coping strategies are considered in this paper: those which divert attention away from the physical sensations associated with the experience (i.e., distraction strategies) and those which focus attention on and attempt to reinterpret such physical sensations (i.e., sensory-focussing strategies). Distraction may be defined as the deployment of attention away from a primary stimulus or experience (e.g., a painful event) and towards an alternative stimulus. According to ‘‘fixed capacity’’ models of attentional processing (e.g., Kahneman & Treisman, 1984; Pashler, 1995) individuals have a limited pool of attentional resources, the allocation of which are under some degree of conscious control. Thus, diverting attention to competing stimuli should lead to fewer attentional resources being allocated to painful experiences. Moreover, given that attention is required for the identification and perception of stimuli (Lachter, Forster, & Ruthruff, 2004), a nociceptive stimulus should be perceived as less painful if there are insufficient remaining attentional resources to devote to it. A variety of different distractors have been used in the management of children’s pain. Typically, these ‘‘distractor’’ stimuli are engaging and pleasant, and include interventions such as non-procedural talk, toys, bubble-blowing, videos, music, imagery, humor, and virtual reality (Kleiber & Harper, 1999; Piira, Hayes, & Goodenough, 2002). However, because the mechanisms that underlie distraction are currently not well understood (Piira et al., 2002), it is difficult to make a priori predictions about the relative effectiveness of such distractors. In contrast to distraction techniques, sensory-focussing strategies involve focussing attention on the physical sensations of pain or discomfort in a non-distressing way. Attending to the sensory aspects of the pain experience may enable an individual to acknowledge these sensations in a concrete, non-emotional manner. Leventhal, Brown, Shacham, and Enquist (1979) have suggested that sensory-focussing strategies work by intercepting or disrupting sensation–distress associations. Sensory-focussing strategies have often been dismissed as counter-intuitive. However, in some contexts, focussing on painful sensations may be more realistic and appropriate than attempting to use distraction-based strategies. Acute pain typically serves the purpose of capturing attention in order to prevent further injury via what may be considered a reflexive, ‘bottom–up’ process (Pashler, Johnston, & Ruthruff, 2001). Even if the painful experience does not signify a threat of injury, ‘top down’ cognitive processes that intentionally focus attention away from the pain experience may require effortful switching that is demanding of central attentional resources (Eccleston, 1995). A number of studies with adults have found that, in some contexts, the use of sensory-focussing strategies may result in greater tolerance, lower distress, and/or lower pain intensity ratings than if using distraction-based interventions (Ahles, Blanchard, & Leventhal, 1983; Blitz & Dinnerstein, 1971; Leventhal et al., 1979; McCaul & Haugtvedt, 1982). One of the few pediatric studies to compare the efficacy of different attentional strategies (Fanurik, Zeltzer, Roberts, & Blount, 1993) found that an imagery-based distraction intervention
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led to greater tolerance for cold-pressor pain than a sensory-focussing intervention. However, these conclusions are compromised by the fact that the distraction and sensory-focussing interventions used by Fanurik differed in many ways in addition to the direction of attention. Most notably, the distraction-based intervention required the self-generation of pleasant images, whereas the sensory-focussing intervention required the child to describe the physical sensations experienced during the cold-pressor procedure. The first of these interventions appears to be a more ‘‘active’’ one involving greater engagement of the child’s attention than the sensoryfocussing intervention. It may have been this difference in the level of attentional engagement that led to the superior outcomes for the distraction condition. The main aim of this study therefore was to carry out a more tightly controlled comparison of the efficacy of distraction and sensoryfocusing techniques in the modification of children’s pain experience. Developing effective techniques for managing children’s pain also involves some consideration of developmental changes in children’s attentional and cognitive abilities. In general, as children get older they report pain experiences to be less intense and show greater pain tolerance (Lander & Fowler-Kerry, 1991). They also develop a greater range of spontaneous strategies for coping with pain (Altshuler, Genevro, Ruble, & Bornstein, 1995; Carroll & Steward, 1984). Coping style refers to one’s preferred, spontaneous approach for responding to stressors such as a painful experience. Studies have found that while some children cope with painful experiences by engaging in distracting activities, other children use approach-based strategies, such as monitoring their experiences or asking questions (e.g., Altshuler et al., 1995; Bernard, Cohen, McClellan, & MacLaren, 2004). The ‘‘congruence hypothesis’’ (Auerbach, Kendall, Cuttler, & Levitt, 1976; Christiano & Russ, 1998) holds that interventions that are matched to an individual’s coping style are likely to lead to better pain outcomes. However, evidence for the congruence hypothesis in pediatrics is equivocal: some studies have found interventions matched to coping style to be more effective than mismatched interventions (e.g., Bernard et al., 2004; Fanurik et al., 1993), while other studies have found little or no support for the congruence hypothesis (e.g., Smith, Akerman, & Blotcky, 1989). A second aim of this study therefore was to examine whether the efficacy of attentional strategies for coping with pain varied as a function of children’s coping style. Using the cold-pressor task (LeBaron, Zeltzer, & Fanurik, 1989; Mitchell, MacDonald, & Brodie, 2004; von Baeyer, Piira, Chambers, Trapanotto, & Zeltzer, 2005; Zeltzer, Fanurik, & LeBaron, 1989) as an experimental pain stimulus, the current study was designed as a controlled evaluation of the effectiveness of two imagery-based interventions for coping with pain which differed in their direction of attentional focus (i.e., towards or away from a pain) but were matched on other important dimensions such as vividness and familiarity. The cold-pressor task is a useful experimental procedure since it minimizes the role of confounding factors such as fatigue, nausea, and fear of medical procedures or hospitalization that may co-occur with pain in clinical contexts. According to the fixed capacity attentional model and previous empirical work (e.g., Fanurik et al., 1993), the distraction condition should produce greater pain tolerance and lower pain intensity ratings than the sensory-focussing condition. Alternatively, if children find it difficult to disengage their attention from painful stimuli, then the sensory-focussing condition would be expected to result in more favorable pain outcomes. Following the congruence hypothesis, it was predicted that children assigned to interventions consistent with their usual coping style would have better pain outcomes. That is, children who indicated on the Pain Coping Questionnaire (PCQ) (Reid,
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Gilbert, & McGrath, 1998) that they usually cope with pain via distraction strategies, would show greater benefit from the distraction intervention (if assigned to that condition) than children who reported making less use of distraction-based strategies outside of the experimental context.
Method Participants A total of 120 healthy, pain-free participants (65 girls, 55 boys) aged 7–14 years (M ¼ 10:16 years, SD ¼ 2:26 years) were recruited from three schools in the south-west of Sydney, Australia. Four parents explicitly declined to give consent for their child to participate in the study. However, it is not known how many children did not return permission notes because they did not want to participate or because their parents withheld consent. The sample was divided into two age categories by median split. Overall, there were 55 children in the ‘‘younger’’ age category (i.e., 7–9 years; 31 girls, 24 boys) and 65 children in the ‘‘older’’ age category (i.e., 10–14 years; 34 girls, 31 boys). Of the younger children, 24 were allocated into the distraction condition, 19 to the sensory-focussing condition, and 12 to the control condition. Of the older children, 25 were allocated into the distraction condition, 28 to the sensory-focussing condition, and 12 to the control condition. A further 93 school children between the ages of 7 and 12 years (41 girls, 52 boys) participated in the pilot-testing of the interventions. None of these children participated in the main experiment. Apparatus The cold-pressor apparatus comprised a water bath (30 cm wide, 50 cm long and 20 cm deep) fitted with a perforated aluminium arm-rest so that each participant’s arm was submerged to the elbow. A pump gently circulated the water to prevent localized warming around the arm. A separate compartment, adjacent to the main water tank but covered with a lid, contained the ice water. A thermostat-controlled electric pump was used to maintain the water temperature at 1071 1C by pumping additional ice water into the main tank as needed. A separate tank of the same size was used as a constant temperature bath, maintained at 3771 1C. The 10 1C cold-pressor task is well suited for use with children, as the duration of discomfort is controlled by the participant, with any discomfort subsiding rapidly once the arm is removed from the water (LeBaron et al., 1989). The physiological effects of this procedure have been documented extensively (Dorn et al., 2004; Lovallo, 1975; Peckerman et al., 1994), and the pain experience considered to be a close analog for many types of naturally occurring pains (Chen, Dworkin, Haug, & Gehrig, 1989). Interventions Four images were described on audiotape. Two images were distraction-based and aimed to focus the child’s attention away from any physical sensations of the cold-pressor task. The other
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two images described scenes intended to orient the child’s attention to the physical sensations resulting from the cold water around the arm. Images were designed to be either neutral or mildly positive in affect.1 The four images used in this study were selected from a pool of eight that were pilot-tested with 93 healthy, pain-free children (7–12 year olds). The intervention images depicted scenes which most Australian children were likely to be familiar with (playing ball in a favorite park, walking home with other children, testing the water temperature of a lake on a cold day, and washing paint off their hand and arm with cold water on a cold day). The four selected images were comparable in terms of amount of perceptual detail. Moreover, the four selected images received comparable scores on ratings of vividness and familiarity based on the pilot study with healthy children. The description of each image lasted between 50 and 60 s. To help children sustain the image, verbal reminders about salient aspects of the image were given at 1 min intervals after the conclusion of the main image instructions (e.g., ‘‘Focus on the cold sensations in your arm as you picture yourself washing off the blue paint’’, and ‘‘Continue to picture yourself walking along the footpath of your way home with the other kids’’). Measures The Pain Coping Questionnaire (PCQ; Reid et al., 1998) is a 39-item self-report measure that assesses how a child usually copes with a pain such as a headache or stomach ache. The PCQ has eight subscales assessing: information-seeking, problem-solving, seeking social support, positive self-statements, behavioral distraction, cognitive distraction, internalizing/ catastrophizing, and externalizing. Given the young age of some of the participants in the current study, a yes/no response format was used rather than the five-point Likert-style format used in the original measure. Each item endorsed affirmatively was given a score of 1. Average scores were then calculated for each subscale. An overall distraction coping style score was also calculated by averaging the cognitive and behavioral distraction subscales. The distraction coping style subscale was found to have a Cronbach’s alpha of 0.77 in the current study. The Coloured Analogue Scale (CAS; McGrath et al., 1996) is a self-report measure of pain intensity, developed with children between the ages of 5 and 16 years of age. The CAS is a 145 mm long vertical wedge which begins with a narrow light pink color on the bottom (‘‘no pain’’) and widens in shape and darkens in color to a deep red on the top (‘‘most pain’’). The intensity or strength of the color represents the strength or intensity of pain. The CAS has been found to have adequate psychophysical properties, as assessed using a calibration task (McGrath et al., 1996). Moreover, children have been found to be able to use the CAS to discriminate between different types of pains (e.g., a broken bone and a stubbed toe) (McGrath et al., 1996). The Vividness of Visual Imagery Questionnaire (VVIQ; Marks, 1973) is a 16-item measure designed to assess an individual’s ability to create vivid visual images. Although initially developed with adult samples, the VVIQ has been validated and found to have adequate test–retest and split-half reliability with children aged 7–16 years (Issac & Marks, 1994). The 1 The neutral–positive affective manipulation was used for a separate study with aims unrelated to this experiment. No significant differences were found between the neutral and positive affect groups on any of the independent or dependent variables considered, as reported in the Results. Hence, all findings were collapsed across the neutral and positive image types. This resulted in the samples for the two intervention groups being twice as large as the control group.
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measure requires the individual to visualize various scenes that are read aloud. Following each item, children rated the vividness of the image on a five-point scale: (1) ‘‘Perfectly clear and as real as normal vision’’, (2) ‘‘Quite clear and real’’, (3) ‘‘Moderately clear and real’’, (4) ‘‘Not so clear or real; quite dim’’ and (5) ‘‘No image at all, you only ‘know’ that you are thinking of the object’’. Low scores represent good visual imagery ability. The current study found the VVIQ to have good internal reliability, with a Cronbach’s alpha of 0.86. Visual Analog Scales (VAS) were used to assess the vividness, familiarity and perceived helpfulness of the images used. Participants were asked to rate the images described on tape using a 0–10 point horizontal VAS from ‘‘not at all’’ on the left to ‘‘extremely’’ on the right, in terms of their vividness, familiarity, and helpfulness in coping with the cold water. The affect or mood associated with the image was also rated from ‘‘negative/sad’’ through to ‘‘positive/happy’’ on a 0–10 scale. Procedure Ethics approval was obtained from the University of New South Wales Research Ethics Committee. After obtaining written parental consent and verbal child assent to participate, children were randomly allocated to the distraction, sensory-focussing or control conditions using a computerized randomization process. All children completed the PCQ for how they usually cope with a headache or stomach ache, and were then administered the VVIQ. The cold-pressor task was then administered individually in a quiet room at the child’s school. Prior to the cold-pressor task, all children were instructed in how to use the CAS and advised that during the cold-pressor procedure they may be prompted at certain times to rate how much pain they were feeling. Children were told that they should not talk when making the ratings, but simply slide the marker on the CAS, using their dominant hand (which was not immersed in the cold water) to show how much pain or discomfort they were feeling in the immersed arm. All participants in the experimental groups then had the opportunity to practice the use of mental imagery via standardized instructions and prompts given through headphones. Children were asked to focus on the practice image for 4 min. Children in the control group sat in the testing room for the same amount of time to control for length of exposure to the experimental equipment. All participants were then provided a brief rationale for relaxation before placing their non-dominant arm in the warm water bath (37 1C) for 2 min to ensure that baseline arm temperatures were constant. During this time, all participants heard a short relaxation technique through their headphones that encouraged slow breathing and use of a muscle relaxation exercise. The purpose of the relaxation exercise was to help place the child in an appropriate frame of mind to give the attentional strategies the best possible chance of being effective. At the end of the 2 min, all participants placed their non-dominant arm in the cold water bath and were instructed to ‘‘Leave your arm in the water for as long as you feel able to’’. The experimenter stood behind the participant, avoiding eye contact with the child during the procedure. As their arm entered the cold water, children in the experimental conditions heard one of four intervention images, followed by prompts to focus on the image, described on tape and played via headphones. Children in the control condition also wore headphones, but did not hear any image described. Pain intensity ratings using the CAS were requested from all participants at 1 min intervals following arm immersion via prompts through headphones. After 4 min all participants were
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asked to withdraw their arm from the cold water if they had not already done so. Pain tolerance was assessed by measuring the total time that the child kept his/her arm in the cold water. After conclusion of the cold-pressor task, children in the experimental groups used the VAS to rate the vividness, familiarity, helpfulness and affect of the images.
Results Participant characteristics Descriptive information for each of the three experimental conditions is presented in Table 1. The mean participant age was quite uniform across the conditions. While slightly more girls were randomly allocated to the control group (66.67%) than to the intervention groups (distraction: 55.10%; sensory-focussing: 46.81%), gender was not significantly associated with pain tolerance or pain intensity ratings. There were no significant differences between the experimental groups on measures of ability to generate visual imagery, F ð4; 119Þ ¼ 0:65, p ¼ 0:63, nor on scores on the distraction subscale of the PCQ (Reid et al., 1998), F ð4; 116Þ ¼ 2:15, p ¼ 0:08. There were no significant differences between the experimental groups on ratings of imagery affect, vividness, Table 1 Demographic information and means (standard deviations) for the individual difference factors and pain outcome measures for the three conditions Distraction (n ¼ 49)a Individual differences Sex (% females) Age (years) PCQ: distraction (0–1) Imagery ability (0–80) Image affect (0–10)b Image vividness (0–10) Image familiarity (0–10) Image helpfulness (0–10) Outcome measures Tolerance (sec) Intensity 1 min (0–10) Intensity 2 min (0–10)c,d Intensity 3 min (0–10)c,e Intensity 4 min (0–10)c,e Average intensityc a
55.1% 10.04 (2.15) 0.70 (0.24) 31.37 (10.69) 7.49 (2.31) 6.43 (2.78) 6.41 (2.78) 6.28 (3.20) 146.9 (97.9) 5.23 (2.89) 4.18 (2.19) 3.91 (2.55) 3.39 (2.35) 4.53 (2.24)
Sensory-focussing (n ¼ 47)a 46.8% 10.43 (2.35) 0.64 (0.27) 35.26 (14.43) 6.87 (2.63) 6.40 (2.65) 6.17 (2.92) 5.64 (3.22) 129.1 (101.8) 5.33 (1.98) 5.14 (1.53) 5.52 (1.89) 5.22 (2.50) 5.48 (1.85)
Control (n ¼ 24)a 66.7% 9.88 (2.26) 0.67 (0.24) 33.13 (11.53) — — — — 104.38 5.48 7.03 6.82 6.40 6.07
(86.6) (2.52) (2.04) (2.09) (1.74) (1.85)
Sample sizes for pain intensity data were lower due to children withdrawing their arms from the cold water over time. See text. b Using a scale where 0 ¼ negative/sad through to 10 ¼ positive/happy. c Significant difference (po0:05) between Distraction and Control conditions. d Significant difference (po0:05) between Sensory-Focussing and Control conditions. e Significant difference (po0:05) between Distraction and Sensory-Focussing.
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familiarity or perceived helpfulness. Preliminary analyses revealed that gender had no main effect on pain tolerance or intensity ratings, and did not interact with the imagery interventions. Overall there was a significant but weak negative correlation between children’s mean ratings of pain intensity and pain tolerance, r ¼ 0:19, po0:05. Pain tolerance Fig. 1 presents Kaplan–Meier survival curves for 7–9 year olds and 10–14 year olds, plotting the proportion of participants that tolerated the cold water over time (in seconds) as a function of experimental condition. It can be seen from the survival curves, that for younger children, those assigned to the distraction condition tended to tolerate the cold water longer than children assigned to the sensory-focussing or control condition. For older children, those assigned to the sensory-focussing condition tended to tolerate the cold water the longest. Overall, the proportion of participants in the control group that maintained their arm in the cold water for the full 4 min was significantly lower than for the two intervention conditions, w2 ¼ 5:36, po0:05. Mean tolerance scores are plotted in Fig. 2 for younger and older children in each of the three conditions. These data were entered into a 3 (distraction, sensory-focussing, and no-imagery control) 2 (younger, older) analysis of variance (ANOVA). Planned comparisons examined the effects of the experimental interventions. The first compared the two attentional interventions with the control. The second compared the distraction and sensory-focussing conditions. Older children had significantly longer pain tolerance times than younger children, F ð1; 114Þ ¼ 21:17, Z2p ¼ 0:16, po0:001. No overall differences were found between the intervention and control conditions in the duration of pain tolerance. There was no overall effect of direction of attention. However, a significant interaction between age and attentional direction was found, F ð1; 114Þ ¼ 11:27, Z2p ¼ 0:09, po0:01. As illustrated in Fig. 2, younger children showed greater
7- to 9-year-olds
10- to 14-year-olds
1.0
1.0 Sensoryfocussing
0.9
Proportion of group in cold water
Proportion of group in cold water
0.9 0.8
Distraction
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Control
0.6 0.5 0.4 0.3 0.2 0.1 0.0
0.8 0.7 0.6 0.5 0.4 0.3
Sensoryfocussing
0.2
Distraction
0.1
Control
0.0 0
60
120 180 Pain tolerance (seconds)
240
0
60
120 180 Pain tolerance (seconds)
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Fig. 1. Survival curves for the three conditions by age group, showing proportion of participants with their hand still in the cold water as a function of time.
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Tolerance (seconds)
240
180 Distraction Sensory-focussing Control
120
60
0 Younger
Older
Fig. 2. Effect of age and direction of attention on pain tolerance, with 95% confidence intervals.
pain tolerance in the distraction condition than in the sensory-focussing condition, whereas the older children showed similar levels of pain tolerance across the two attentional manipulations. A Tukey HSD test confirmed that, for younger children only, the difference between tolerance scores in the sensory-focussing versus the distraction conditions was statistically significant, po0:001. Moreover, younger children in the distraction condition (po0:05), but not those in the sensory-focussing condition (p ¼ 0:23), showed greater pain tolerance than did the controls. Correlational analyses also revealed that within the sensory-focussing group, there was a significant correlation between age and tolerance (r ¼ 0:72, po0:001), whereas this correlation was not significant for participants in the distraction condition (r ¼ 0:23). Pain intensity Pain intensity ratings for participants in the three groups across the four occasions of measurement during the cold-pressor task are presented in Fig. 3. The sample sizes for the intensity ratings taken at 1, 2, 3 and 4 min were 70, 59, 53 and 50, respectively. Rating data for each measurement occasion were entered into a 3 (condition) 2 (age) ANOVA with the same planned comparisons that were used for tolerance. Pain intensity ratings showed no differences between three conditions at 1 min. However, children in the control condition had significantly higher pain intensity ratings than participants in the imagery intervention conditions at 2 min, F ð1; 56Þ ¼ 11:06, Z2p ¼ 0:16, po0:01, and at 3 min, F ð1; 50Þ ¼ 5:30, Z2p ¼ 0:001, po0:05. By 4 min, within the control group, all but five participants had removed their arm from the cold water and so no comparisons of intensity ratings were carried out. No significant differences in pain intensity were found between the two intervention conditions. Role of coping style in older children For the imagery intervention groups, two 2 2 ANOVAs were conducted to assess the effects of direction of attention (distraction versus sensory-focussing) and distraction-based coping (low versus high frequency of use) in everyday pain contexts on pain tolerance and ratings of pain
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10 9 8 7 6 5 4 3 2 1 0
Condition: Distraction Sensoryfocussing Control
1min
2min
3min
4min
Time since arm immersion
Fig. 3. Pain intensity ratings for the distraction, sensory-focussing and control groups. The number of participants maintaining their arm in the cold water decreased over time. The rate of attrition differed across groups, with only 20.83% of participants in the control group maintaining their arm in the cold water for 4 min, as compared with 48.98% and 44.68% for the distraction and sensory-focussing groups, respectively.
Tolerance (seconds)
240 180
Condition Distraction
120
Sensory-Focussing Control
60 0 Low
High
Fig. 4. Coping style and direction of attention on pain tolerance of older children (10–14 years), with 95% confidence intervals.
intensity. Children were classified as making relatively low or high use of distraction strategies based on a median split of scores for the distraction factor of the PCQ (Reid et al., 1998). These analyses were conducted only for older children (10–14 years), given that the sensory-focussing intervention was generally unhelpful for younger children (see Fig. 2). It was expected that low distractors would rate the distraction image as being less helpful and less vivid than high distractors. These differences within the intervention conditions were assessed using post hoc analyses of variance, but were not found to be statistically significant. Fig. 4 presents mean pain tolerance scores for children who did or did not make frequent use of distraction strategies for everyday pains such as headaches or stomach aches. There was no main effect of coping style on either pain tolerance or average pain intensity. Coping style did, however, show a significant interaction with direction of attention for pain tolerance, F ð1; 48Þ ¼ 5:72, Z2p ¼ 0:12, po0:05, but not with average pain intensity, F ð1; 43Þ ¼ 1:00, Z2p ¼ 0:02, p ¼ 0:32. In the case of the ‘‘high distractors’’ (those who reported frequent use of distraction coping strategies on
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the PCQ), there was little difference in pain tolerance across the experimental intervention and control conditions. For the children showing a ‘‘low distractor’’ pattern on the PCQ, the sensoryfocussing intervention produced higher pain tolerance than either the distraction intervention or the control condition.
Discussion The current study was designed to investigate the efficacy of two attentional strategies, namely distraction and sensory-focussing, on children’s coping with experimentally induced pain. The fixed capacity model of attention predicted that the distraction intervention would result in greater pain tolerance and lower pain intensity ratings than the sensory-focussing and control conditions. With regard to pain tolerance, this prediction was supported for younger children (7–9 year olds) but not for older children (10–14 year olds). Consistent with the results of Fanurik et al. (1993), the current study found younger children to benefit more from the distraction rather than the sensory-focussing intervention. In contrast, older children overall showed similar levels of pain tolerance irrespective of whether they were in the sensory-focussing or distraction condition. With regard to pain intensity ratings, consistent with the fixed capacity model of attention, children in the distraction condition reported lower pain intensity after 1 min of exposure to the cold water than children in other conditions. It is noteworthy that older children generally showed longer pain tolerance than younger children, given that both younger and older children gave similar pain intensity ratings during the cold-pressor task. This finding may reflect the fact that the pain intensity ratings were primarily a measure of the sensory dimension of pain, whereas pain tolerance may reflect the motivational and cognitive components of pain (Handwerker & Kobal, 1993). Although younger and older children may have experienced similar physical sensations of cold-pressor pain, older children may have been more motivated to keep their arm immersed for as long as possible, or were better able to utilize coping strategies to tolerate the discomfort. Age was found to have a profound influence on the efficacy of the attentional conditions on pain tolerance, with older children benefiting from both the distraction and sensory-focussing interventions, whereas younger children benefited only from the distraction intervention. The apparent greater flexibility in use of different coping approaches demonstrated by the older children may be related to their greater life experience with painful events, or their superior cognitive-developmental abilities. In particular, the ability to distinguish between the sensory and emotional aspects of pain is likely to be necessary for the use of sensory-focussing strategies for pain management, given that sensory-focussing strategies typically involve a reinterpretation of the somatic aspects of pain in order to reduce emotional distress. Previous work suggests that children younger than about 8 years of age have difficulty in distinguishing between these pain dimensions (Goodenough et al., 1999). Personal coping style was found to influence which pain coping intervention resulted in the best outcomes for the child. The current study found some evidence to support the congruence hypothesis (Auerbach et al., 1976; Christiano & Russ, 1998), whereby matching interventions to personal coping style resulted in more favorable outcomes. Older children who reported that they made little use of distraction-based strategies when experiencing common pains such as a
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headache or stomach ache had better pain outcomes when assigned to the sensory-focussing rather than distraction condition. Older children who reported typically making greater use of distraction-based strategies when experiencing pain showed greater pain tolerance when assigned to the distraction rather than the sensory-focussing condition. There are a number of possible explanations for this pattern of results. First, children who reported that they generally made little use of distraction strategies may not have had as much practice in the use of distraction-based strategies, and hence may have found it more difficult to direct their attention externally, away from the physical sensations. Second, these children may have had a greater tendency and preference to monitor the situation and what they were experiencing in order to maintain a sense of control and equilibrium. Thus, it may have been more difficult for them to imaginatively engage in any ‘‘external’’ story or image. A number of factors related to the selection of participants and experimental pain procedure need to be considered when generalizing the results to pediatric patients experiencing clinical pain. First, the child participants were volunteers informed that they would undergo a painful experience. Hence, children who perceived that they cope poorly with pain or highly anxious children may have declined to participate. Second, study participants were aware that the pain from the cold-pressor task was time-limited and brief. This may have made them less anxious and distressed than would be the case in many clinical contexts. Third, obtaining repeated pain intensity ratings during the cold-pressor task may have made it more difficult for participants in the distraction condition to focus away from the pain. The rating procedure may entail reactive effects of measurement, i.e., changes produced by the measurement procedure itself (von Baeyer, 1994). Hence, the pain outcomes for the distraction group may actually under-estimate the benefits of such an intervention. Nevertheless, the results of the study do suggest that encouraging children to use pain coping strategies involving the manipulation of attention should not be done on a ‘‘one size fits all’’ basis. Distraction-based strategies would appear to be the intervention of choice for younger children and those who employ distraction routinely as a way of coping with pain and stress. Sensoryfocussing, on the other hand, may be helpful for some older children, particularly those children who have little previous experience of distraction strategies. The fact that pain intensity ratings were significantly lower after 1 min in the distraction condition, relative to the sensory-focussing and control conditions, has potential implications for the timing of the onset of distraction interventions. Clearly, it may take children a few minutes to become sufficiently engaged in a distraction image in order to obtain maximal benefit. Further research is needed to assess the generalizability of these findings to clinical contexts. Moreover, a better understanding of the mechanisms by which attentional coping strategies influence children’s pain outcomes is needed in order to understand why particular strategies may be more or less helpful for particular children and in particular contexts.
Acknowledgments The authors are grateful to the staff and students at All Saints Catholic Primary School, All Saints Catholic Girls’ College, and All Saints Catholic Boys’ College in Liverpool, Australia. Thanks also go to Theona Bustos, Anna Cole and Dayna McGill for their assistance with data
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collection. The support of Associate Professor David Champion is also gratefully acknowledged. This work was carried out as part of the first author’s doctoral work at the University of New South Wales, Australia, under the supervision of Drs Brett Hayes and Belinda Goodenough. The first author gratefully acknowledges receiving fellowship support from the Mayday Foundation to participate in the Canadian Institutes of Health Research Strategic Training Program—Pain in Child Health.
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Behaviour Research and Therapy 44 (2006) 835–848 www.elsevier.com/locate/brat
Effects of attentional direction, age, and coping style on cold-pressor pain in children Tiina Piiraa,b,, Brett Hayesb, Belinda Goodenoughb,c, Carl L. von Baeyerd a
Pain Research Unit, Sydney Children’s Hospital, High Street, Randwick NSW 2031, Australia b School of Psychology, University of New South Wales, Sydney, Australia c Centre for Children’s Cancer & Blood Disorders, Sydney Children’s Hospital, Randwick, Australia d Departments of Psychology and Pediatrics, University of Saskatchewan, Saskatoon, Canada Received 12 January 2004; received in revised form 6 March 2005; accepted 6 March 2005
Abstract This study assessed the relative efficacy of two imagery-based attentional strategies for modifying pain experience in children. Children aged 7–14 years (n ¼ 120) were randomly assigned to one of three conditions: distraction, sensory-focussing or control (no imagery). The distraction condition prompted children to focus their attention externally; the sensory-focussing condition prompted the child to focus internally on physical sensations. Self-report measures of pain coping style preferences and imagery ability were completed. Children’s pain tolerance and perceptions of pain intensity were assessed using a 10 1C cold-pressor task. Results showed pain intensity ratings after 1 min were lower for both intervention conditions than for the controls. Younger children (7–9 years) showed higher pain tolerance in the distraction condition than in the sensory-focussing condition, whereas both interventions were equally effective for older children (10–14 years). Among older children, coping style interacted with the intervention type: in the sensory-focussing condition, pain tolerance was negatively associated with self-reported distraction-based coping style, whereas in the distraction condition this association was positive. The results are interpreted with reference to current models of attention. The implications for use of attentional strategies in helping children to cope with clinical pain are discussed. r 2005 Elsevier Ltd. All rights reserved. Keywords: Attention; Child; Cold-pressor; Coping; Distraction; Pain
Corresponding author. Pain Research Unit, Sydney Children’s Hospital, High Street, Randwick NSW 2031,
Australia. Tel.: +61 2 9382 1585; fax: +61 2 9382 7946. E-mail address: [email protected] (T. Piira). 0005-7967/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.brat.2005.03.013
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Introduction Instruction in attentional coping strategies, such as distraction, is often used in the clinical management of children’s acute pain. However, the mechanisms by which coping strategies may influence children’s pain outcomes are not well understood. Hence, it is not always clear which types of attentional strategies are likely to be most effective in pediatric pain. Two types of attentional coping strategies are considered in this paper: those which divert attention away from the physical sensations associated with the experience (i.e., distraction strategies) and those which focus attention on and attempt to reinterpret such physical sensations (i.e., sensory-focussing strategies). Distraction may be defined as the deployment of attention away from a primary stimulus or experience (e.g., a painful event) and towards an alternative stimulus. According to ‘‘fixed capacity’’ models of attentional processing (e.g., Kahneman & Treisman, 1984; Pashler, 1995) individuals have a limited pool of attentional resources, the allocation of which are under some degree of conscious control. Thus, diverting attention to competing stimuli should lead to fewer attentional resources being allocated to painful experiences. Moreover, given that attention is required for the identification and perception of stimuli (Lachter, Forster, & Ruthruff, 2004), a nociceptive stimulus should be perceived as less painful if there are insufficient remaining attentional resources to devote to it. A variety of different distractors have been used in the management of children’s pain. Typically, these ‘‘distractor’’ stimuli are engaging and pleasant, and include interventions such as non-procedural talk, toys, bubble-blowing, videos, music, imagery, humor, and virtual reality (Kleiber & Harper, 1999; Piira, Hayes, & Goodenough, 2002). However, because the mechanisms that underlie distraction are currently not well understood (Piira et al., 2002), it is difficult to make a priori predictions about the relative effectiveness of such distractors. In contrast to distraction techniques, sensory-focussing strategies involve focussing attention on the physical sensations of pain or discomfort in a non-distressing way. Attending to the sensory aspects of the pain experience may enable an individual to acknowledge these sensations in a concrete, non-emotional manner. Leventhal, Brown, Shacham, and Enquist (1979) have suggested that sensory-focussing strategies work by intercepting or disrupting sensation–distress associations. Sensory-focussing strategies have often been dismissed as counter-intuitive. However, in some contexts, focussing on painful sensations may be more realistic and appropriate than attempting to use distraction-based strategies. Acute pain typically serves the purpose of capturing attention in order to prevent further injury via what may be considered a reflexive, ‘bottom–up’ process (Pashler, Johnston, & Ruthruff, 2001). Even if the painful experience does not signify a threat of injury, ‘top down’ cognitive processes that intentionally focus attention away from the pain experience may require effortful switching that is demanding of central attentional resources (Eccleston, 1995). A number of studies with adults have found that, in some contexts, the use of sensory-focussing strategies may result in greater tolerance, lower distress, and/or lower pain intensity ratings than if using distraction-based interventions (Ahles, Blanchard, & Leventhal, 1983; Blitz & Dinnerstein, 1971; Leventhal et al., 1979; McCaul & Haugtvedt, 1982). One of the few pediatric studies to compare the efficacy of different attentional strategies (Fanurik, Zeltzer, Roberts, & Blount, 1993) found that an imagery-based distraction intervention
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led to greater tolerance for cold-pressor pain than a sensory-focussing intervention. However, these conclusions are compromised by the fact that the distraction and sensory-focussing interventions used by Fanurik differed in many ways in addition to the direction of attention. Most notably, the distraction-based intervention required the self-generation of pleasant images, whereas the sensory-focussing intervention required the child to describe the physical sensations experienced during the cold-pressor procedure. The first of these interventions appears to be a more ‘‘active’’ one involving greater engagement of the child’s attention than the sensoryfocussing intervention. It may have been this difference in the level of attentional engagement that led to the superior outcomes for the distraction condition. The main aim of this study therefore was to carry out a more tightly controlled comparison of the efficacy of distraction and sensoryfocusing techniques in the modification of children’s pain experience. Developing effective techniques for managing children’s pain also involves some consideration of developmental changes in children’s attentional and cognitive abilities. In general, as children get older they report pain experiences to be less intense and show greater pain tolerance (Lander & Fowler-Kerry, 1991). They also develop a greater range of spontaneous strategies for coping with pain (Altshuler, Genevro, Ruble, & Bornstein, 1995; Carroll & Steward, 1984). Coping style refers to one’s preferred, spontaneous approach for responding to stressors such as a painful experience. Studies have found that while some children cope with painful experiences by engaging in distracting activities, other children use approach-based strategies, such as monitoring their experiences or asking questions (e.g., Altshuler et al., 1995; Bernard, Cohen, McClellan, & MacLaren, 2004). The ‘‘congruence hypothesis’’ (Auerbach, Kendall, Cuttler, & Levitt, 1976; Christiano & Russ, 1998) holds that interventions that are matched to an individual’s coping style are likely to lead to better pain outcomes. However, evidence for the congruence hypothesis in pediatrics is equivocal: some studies have found interventions matched to coping style to be more effective than mismatched interventions (e.g., Bernard et al., 2004; Fanurik et al., 1993), while other studies have found little or no support for the congruence hypothesis (e.g., Smith, Akerman, & Blotcky, 1989). A second aim of this study therefore was to examine whether the efficacy of attentional strategies for coping with pain varied as a function of children’s coping style. Using the cold-pressor task (LeBaron, Zeltzer, & Fanurik, 1989; Mitchell, MacDonald, & Brodie, 2004; von Baeyer, Piira, Chambers, Trapanotto, & Zeltzer, 2005; Zeltzer, Fanurik, & LeBaron, 1989) as an experimental pain stimulus, the current study was designed as a controlled evaluation of the effectiveness of two imagery-based interventions for coping with pain which differed in their direction of attentional focus (i.e., towards or away from a pain) but were matched on other important dimensions such as vividness and familiarity. The cold-pressor task is a useful experimental procedure since it minimizes the role of confounding factors such as fatigue, nausea, and fear of medical procedures or hospitalization that may co-occur with pain in clinical contexts. According to the fixed capacity attentional model and previous empirical work (e.g., Fanurik et al., 1993), the distraction condition should produce greater pain tolerance and lower pain intensity ratings than the sensory-focussing condition. Alternatively, if children find it difficult to disengage their attention from painful stimuli, then the sensory-focussing condition would be expected to result in more favorable pain outcomes. Following the congruence hypothesis, it was predicted that children assigned to interventions consistent with their usual coping style would have better pain outcomes. That is, children who indicated on the Pain Coping Questionnaire (PCQ) (Reid,
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Gilbert, & McGrath, 1998) that they usually cope with pain via distraction strategies, would show greater benefit from the distraction intervention (if assigned to that condition) than children who reported making less use of distraction-based strategies outside of the experimental context.
Method Participants A total of 120 healthy, pain-free participants (65 girls, 55 boys) aged 7–14 years (M ¼ 10:16 years, SD ¼ 2:26 years) were recruited from three schools in the south-west of Sydney, Australia. Four parents explicitly declined to give consent for their child to participate in the study. However, it is not known how many children did not return permission notes because they did not want to participate or because their parents withheld consent. The sample was divided into two age categories by median split. Overall, there were 55 children in the ‘‘younger’’ age category (i.e., 7–9 years; 31 girls, 24 boys) and 65 children in the ‘‘older’’ age category (i.e., 10–14 years; 34 girls, 31 boys). Of the younger children, 24 were allocated into the distraction condition, 19 to the sensory-focussing condition, and 12 to the control condition. Of the older children, 25 were allocated into the distraction condition, 28 to the sensory-focussing condition, and 12 to the control condition. A further 93 school children between the ages of 7 and 12 years (41 girls, 52 boys) participated in the pilot-testing of the interventions. None of these children participated in the main experiment. Apparatus The cold-pressor apparatus comprised a water bath (30 cm wide, 50 cm long and 20 cm deep) fitted with a perforated aluminium arm-rest so that each participant’s arm was submerged to the elbow. A pump gently circulated the water to prevent localized warming around the arm. A separate compartment, adjacent to the main water tank but covered with a lid, contained the ice water. A thermostat-controlled electric pump was used to maintain the water temperature at 1071 1C by pumping additional ice water into the main tank as needed. A separate tank of the same size was used as a constant temperature bath, maintained at 3771 1C. The 10 1C cold-pressor task is well suited for use with children, as the duration of discomfort is controlled by the participant, with any discomfort subsiding rapidly once the arm is removed from the water (LeBaron et al., 1989). The physiological effects of this procedure have been documented extensively (Dorn et al., 2004; Lovallo, 1975; Peckerman et al., 1994), and the pain experience considered to be a close analog for many types of naturally occurring pains (Chen, Dworkin, Haug, & Gehrig, 1989). Interventions Four images were described on audiotape. Two images were distraction-based and aimed to focus the child’s attention away from any physical sensations of the cold-pressor task. The other
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two images described scenes intended to orient the child’s attention to the physical sensations resulting from the cold water around the arm. Images were designed to be either neutral or mildly positive in affect.1 The four images used in this study were selected from a pool of eight that were pilot-tested with 93 healthy, pain-free children (7–12 year olds). The intervention images depicted scenes which most Australian children were likely to be familiar with (playing ball in a favorite park, walking home with other children, testing the water temperature of a lake on a cold day, and washing paint off their hand and arm with cold water on a cold day). The four selected images were comparable in terms of amount of perceptual detail. Moreover, the four selected images received comparable scores on ratings of vividness and familiarity based on the pilot study with healthy children. The description of each image lasted between 50 and 60 s. To help children sustain the image, verbal reminders about salient aspects of the image were given at 1 min intervals after the conclusion of the main image instructions (e.g., ‘‘Focus on the cold sensations in your arm as you picture yourself washing off the blue paint’’, and ‘‘Continue to picture yourself walking along the footpath of your way home with the other kids’’). Measures The Pain Coping Questionnaire (PCQ; Reid et al., 1998) is a 39-item self-report measure that assesses how a child usually copes with a pain such as a headache or stomach ache. The PCQ has eight subscales assessing: information-seeking, problem-solving, seeking social support, positive self-statements, behavioral distraction, cognitive distraction, internalizing/ catastrophizing, and externalizing. Given the young age of some of the participants in the current study, a yes/no response format was used rather than the five-point Likert-style format used in the original measure. Each item endorsed affirmatively was given a score of 1. Average scores were then calculated for each subscale. An overall distraction coping style score was also calculated by averaging the cognitive and behavioral distraction subscales. The distraction coping style subscale was found to have a Cronbach’s alpha of 0.77 in the current study. The Coloured Analogue Scale (CAS; McGrath et al., 1996) is a self-report measure of pain intensity, developed with children between the ages of 5 and 16 years of age. The CAS is a 145 mm long vertical wedge which begins with a narrow light pink color on the bottom (‘‘no pain’’) and widens in shape and darkens in color to a deep red on the top (‘‘most pain’’). The intensity or strength of the color represents the strength or intensity of pain. The CAS has been found to have adequate psychophysical properties, as assessed using a calibration task (McGrath et al., 1996). Moreover, children have been found to be able to use the CAS to discriminate between different types of pains (e.g., a broken bone and a stubbed toe) (McGrath et al., 1996). The Vividness of Visual Imagery Questionnaire (VVIQ; Marks, 1973) is a 16-item measure designed to assess an individual’s ability to create vivid visual images. Although initially developed with adult samples, the VVIQ has been validated and found to have adequate test–retest and split-half reliability with children aged 7–16 years (Issac & Marks, 1994). The 1 The neutral–positive affective manipulation was used for a separate study with aims unrelated to this experiment. No significant differences were found between the neutral and positive affect groups on any of the independent or dependent variables considered, as reported in the Results. Hence, all findings were collapsed across the neutral and positive image types. This resulted in the samples for the two intervention groups being twice as large as the control group.
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measure requires the individual to visualize various scenes that are read aloud. Following each item, children rated the vividness of the image on a five-point scale: (1) ‘‘Perfectly clear and as real as normal vision’’, (2) ‘‘Quite clear and real’’, (3) ‘‘Moderately clear and real’’, (4) ‘‘Not so clear or real; quite dim’’ and (5) ‘‘No image at all, you only ‘know’ that you are thinking of the object’’. Low scores represent good visual imagery ability. The current study found the VVIQ to have good internal reliability, with a Cronbach’s alpha of 0.86. Visual Analog Scales (VAS) were used to assess the vividness, familiarity and perceived helpfulness of the images used. Participants were asked to rate the images described on tape using a 0–10 point horizontal VAS from ‘‘not at all’’ on the left to ‘‘extremely’’ on the right, in terms of their vividness, familiarity, and helpfulness in coping with the cold water. The affect or mood associated with the image was also rated from ‘‘negative/sad’’ through to ‘‘positive/happy’’ on a 0–10 scale. Procedure Ethics approval was obtained from the University of New South Wales Research Ethics Committee. After obtaining written parental consent and verbal child assent to participate, children were randomly allocated to the distraction, sensory-focussing or control conditions using a computerized randomization process. All children completed the PCQ for how they usually cope with a headache or stomach ache, and were then administered the VVIQ. The cold-pressor task was then administered individually in a quiet room at the child’s school. Prior to the cold-pressor task, all children were instructed in how to use the CAS and advised that during the cold-pressor procedure they may be prompted at certain times to rate how much pain they were feeling. Children were told that they should not talk when making the ratings, but simply slide the marker on the CAS, using their dominant hand (which was not immersed in the cold water) to show how much pain or discomfort they were feeling in the immersed arm. All participants in the experimental groups then had the opportunity to practice the use of mental imagery via standardized instructions and prompts given through headphones. Children were asked to focus on the practice image for 4 min. Children in the control group sat in the testing room for the same amount of time to control for length of exposure to the experimental equipment. All participants were then provided a brief rationale for relaxation before placing their non-dominant arm in the warm water bath (37 1C) for 2 min to ensure that baseline arm temperatures were constant. During this time, all participants heard a short relaxation technique through their headphones that encouraged slow breathing and use of a muscle relaxation exercise. The purpose of the relaxation exercise was to help place the child in an appropriate frame of mind to give the attentional strategies the best possible chance of being effective. At the end of the 2 min, all participants placed their non-dominant arm in the cold water bath and were instructed to ‘‘Leave your arm in the water for as long as you feel able to’’. The experimenter stood behind the participant, avoiding eye contact with the child during the procedure. As their arm entered the cold water, children in the experimental conditions heard one of four intervention images, followed by prompts to focus on the image, described on tape and played via headphones. Children in the control condition also wore headphones, but did not hear any image described. Pain intensity ratings using the CAS were requested from all participants at 1 min intervals following arm immersion via prompts through headphones. After 4 min all participants were
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asked to withdraw their arm from the cold water if they had not already done so. Pain tolerance was assessed by measuring the total time that the child kept his/her arm in the cold water. After conclusion of the cold-pressor task, children in the experimental groups used the VAS to rate the vividness, familiarity, helpfulness and affect of the images.
Results Participant characteristics Descriptive information for each of the three experimental conditions is presented in Table 1. The mean participant age was quite uniform across the conditions. While slightly more girls were randomly allocated to the control group (66.67%) than to the intervention groups (distraction: 55.10%; sensory-focussing: 46.81%), gender was not significantly associated with pain tolerance or pain intensity ratings. There were no significant differences between the experimental groups on measures of ability to generate visual imagery, F ð4; 119Þ ¼ 0:65, p ¼ 0:63, nor on scores on the distraction subscale of the PCQ (Reid et al., 1998), F ð4; 116Þ ¼ 2:15, p ¼ 0:08. There were no significant differences between the experimental groups on ratings of imagery affect, vividness, Table 1 Demographic information and means (standard deviations) for the individual difference factors and pain outcome measures for the three conditions Distraction (n ¼ 49)a Individual differences Sex (% females) Age (years) PCQ: distraction (0–1) Imagery ability (0–80) Image affect (0–10)b Image vividness (0–10) Image familiarity (0–10) Image helpfulness (0–10) Outcome measures Tolerance (sec) Intensity 1 min (0–10) Intensity 2 min (0–10)c,d Intensity 3 min (0–10)c,e Intensity 4 min (0–10)c,e Average intensityc a
55.1% 10.04 (2.15) 0.70 (0.24) 31.37 (10.69) 7.49 (2.31) 6.43 (2.78) 6.41 (2.78) 6.28 (3.20) 146.9 (97.9) 5.23 (2.89) 4.18 (2.19) 3.91 (2.55) 3.39 (2.35) 4.53 (2.24)
Sensory-focussing (n ¼ 47)a 46.8% 10.43 (2.35) 0.64 (0.27) 35.26 (14.43) 6.87 (2.63) 6.40 (2.65) 6.17 (2.92) 5.64 (3.22) 129.1 (101.8) 5.33 (1.98) 5.14 (1.53) 5.52 (1.89) 5.22 (2.50) 5.48 (1.85)
Control (n ¼ 24)a 66.7% 9.88 (2.26) 0.67 (0.24) 33.13 (11.53) — — — — 104.38 5.48 7.03 6.82 6.40 6.07
(86.6) (2.52) (2.04) (2.09) (1.74) (1.85)
Sample sizes for pain intensity data were lower due to children withdrawing their arms from the cold water over time. See text. b Using a scale where 0 ¼ negative/sad through to 10 ¼ positive/happy. c Significant difference (po0:05) between Distraction and Control conditions. d Significant difference (po0:05) between Sensory-Focussing and Control conditions. e Significant difference (po0:05) between Distraction and Sensory-Focussing.
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familiarity or perceived helpfulness. Preliminary analyses revealed that gender had no main effect on pain tolerance or intensity ratings, and did not interact with the imagery interventions. Overall there was a significant but weak negative correlation between children’s mean ratings of pain intensity and pain tolerance, r ¼ 0:19, po0:05. Pain tolerance Fig. 1 presents Kaplan–Meier survival curves for 7–9 year olds and 10–14 year olds, plotting the proportion of participants that tolerated the cold water over time (in seconds) as a function of experimental condition. It can be seen from the survival curves, that for younger children, those assigned to the distraction condition tended to tolerate the cold water longer than children assigned to the sensory-focussing or control condition. For older children, those assigned to the sensory-focussing condition tended to tolerate the cold water the longest. Overall, the proportion of participants in the control group that maintained their arm in the cold water for the full 4 min was significantly lower than for the two intervention conditions, w2 ¼ 5:36, po0:05. Mean tolerance scores are plotted in Fig. 2 for younger and older children in each of the three conditions. These data were entered into a 3 (distraction, sensory-focussing, and no-imagery control) 2 (younger, older) analysis of variance (ANOVA). Planned comparisons examined the effects of the experimental interventions. The first compared the two attentional interventions with the control. The second compared the distraction and sensory-focussing conditions. Older children had significantly longer pain tolerance times than younger children, F ð1; 114Þ ¼ 21:17, Z2p ¼ 0:16, po0:001. No overall differences were found between the intervention and control conditions in the duration of pain tolerance. There was no overall effect of direction of attention. However, a significant interaction between age and attentional direction was found, F ð1; 114Þ ¼ 11:27, Z2p ¼ 0:09, po0:01. As illustrated in Fig. 2, younger children showed greater
7- to 9-year-olds
10- to 14-year-olds
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1.0 Sensoryfocussing
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Proportion of group in cold water
Proportion of group in cold water
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0.6 0.5 0.4 0.3 0.2 0.1 0.0
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0.0 0
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120 180 Pain tolerance (seconds)
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Fig. 1. Survival curves for the three conditions by age group, showing proportion of participants with their hand still in the cold water as a function of time.
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Fig. 2. Effect of age and direction of attention on pain tolerance, with 95% confidence intervals.
pain tolerance in the distraction condition than in the sensory-focussing condition, whereas the older children showed similar levels of pain tolerance across the two attentional manipulations. A Tukey HSD test confirmed that, for younger children only, the difference between tolerance scores in the sensory-focussing versus the distraction conditions was statistically significant, po0:001. Moreover, younger children in the distraction condition (po0:05), but not those in the sensory-focussing condition (p ¼ 0:23), showed greater pain tolerance than did the controls. Correlational analyses also revealed that within the sensory-focussing group, there was a significant correlation between age and tolerance (r ¼ 0:72, po0:001), whereas this correlation was not significant for participants in the distraction condition (r ¼ 0:23). Pain intensity Pain intensity ratings for participants in the three groups across the four occasions of measurement during the cold-pressor task are presented in Fig. 3. The sample sizes for the intensity ratings taken at 1, 2, 3 and 4 min were 70, 59, 53 and 50, respectively. Rating data for each measurement occasion were entered into a 3 (condition) 2 (age) ANOVA with the same planned comparisons that were used for tolerance. Pain intensity ratings showed no differences between three conditions at 1 min. However, children in the control condition had significantly higher pain intensity ratings than participants in the imagery intervention conditions at 2 min, F ð1; 56Þ ¼ 11:06, Z2p ¼ 0:16, po0:01, and at 3 min, F ð1; 50Þ ¼ 5:30, Z2p ¼ 0:001, po0:05. By 4 min, within the control group, all but five participants had removed their arm from the cold water and so no comparisons of intensity ratings were carried out. No significant differences in pain intensity were found between the two intervention conditions. Role of coping style in older children For the imagery intervention groups, two 2 2 ANOVAs were conducted to assess the effects of direction of attention (distraction versus sensory-focussing) and distraction-based coping (low versus high frequency of use) in everyday pain contexts on pain tolerance and ratings of pain
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Condition: Distraction Sensoryfocussing Control
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2min
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Fig. 3. Pain intensity ratings for the distraction, sensory-focussing and control groups. The number of participants maintaining their arm in the cold water decreased over time. The rate of attrition differed across groups, with only 20.83% of participants in the control group maintaining their arm in the cold water for 4 min, as compared with 48.98% and 44.68% for the distraction and sensory-focussing groups, respectively.
Tolerance (seconds)
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Condition Distraction
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Sensory-Focussing Control
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Fig. 4. Coping style and direction of attention on pain tolerance of older children (10–14 years), with 95% confidence intervals.
intensity. Children were classified as making relatively low or high use of distraction strategies based on a median split of scores for the distraction factor of the PCQ (Reid et al., 1998). These analyses were conducted only for older children (10–14 years), given that the sensory-focussing intervention was generally unhelpful for younger children (see Fig. 2). It was expected that low distractors would rate the distraction image as being less helpful and less vivid than high distractors. These differences within the intervention conditions were assessed using post hoc analyses of variance, but were not found to be statistically significant. Fig. 4 presents mean pain tolerance scores for children who did or did not make frequent use of distraction strategies for everyday pains such as headaches or stomach aches. There was no main effect of coping style on either pain tolerance or average pain intensity. Coping style did, however, show a significant interaction with direction of attention for pain tolerance, F ð1; 48Þ ¼ 5:72, Z2p ¼ 0:12, po0:05, but not with average pain intensity, F ð1; 43Þ ¼ 1:00, Z2p ¼ 0:02, p ¼ 0:32. In the case of the ‘‘high distractors’’ (those who reported frequent use of distraction coping strategies on
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the PCQ), there was little difference in pain tolerance across the experimental intervention and control conditions. For the children showing a ‘‘low distractor’’ pattern on the PCQ, the sensoryfocussing intervention produced higher pain tolerance than either the distraction intervention or the control condition.
Discussion The current study was designed to investigate the efficacy of two attentional strategies, namely distraction and sensory-focussing, on children’s coping with experimentally induced pain. The fixed capacity model of attention predicted that the distraction intervention would result in greater pain tolerance and lower pain intensity ratings than the sensory-focussing and control conditions. With regard to pain tolerance, this prediction was supported for younger children (7–9 year olds) but not for older children (10–14 year olds). Consistent with the results of Fanurik et al. (1993), the current study found younger children to benefit more from the distraction rather than the sensory-focussing intervention. In contrast, older children overall showed similar levels of pain tolerance irrespective of whether they were in the sensory-focussing or distraction condition. With regard to pain intensity ratings, consistent with the fixed capacity model of attention, children in the distraction condition reported lower pain intensity after 1 min of exposure to the cold water than children in other conditions. It is noteworthy that older children generally showed longer pain tolerance than younger children, given that both younger and older children gave similar pain intensity ratings during the cold-pressor task. This finding may reflect the fact that the pain intensity ratings were primarily a measure of the sensory dimension of pain, whereas pain tolerance may reflect the motivational and cognitive components of pain (Handwerker & Kobal, 1993). Although younger and older children may have experienced similar physical sensations of cold-pressor pain, older children may have been more motivated to keep their arm immersed for as long as possible, or were better able to utilize coping strategies to tolerate the discomfort. Age was found to have a profound influence on the efficacy of the attentional conditions on pain tolerance, with older children benefiting from both the distraction and sensory-focussing interventions, whereas younger children benefited only from the distraction intervention. The apparent greater flexibility in use of different coping approaches demonstrated by the older children may be related to their greater life experience with painful events, or their superior cognitive-developmental abilities. In particular, the ability to distinguish between the sensory and emotional aspects of pain is likely to be necessary for the use of sensory-focussing strategies for pain management, given that sensory-focussing strategies typically involve a reinterpretation of the somatic aspects of pain in order to reduce emotional distress. Previous work suggests that children younger than about 8 years of age have difficulty in distinguishing between these pain dimensions (Goodenough et al., 1999). Personal coping style was found to influence which pain coping intervention resulted in the best outcomes for the child. The current study found some evidence to support the congruence hypothesis (Auerbach et al., 1976; Christiano & Russ, 1998), whereby matching interventions to personal coping style resulted in more favorable outcomes. Older children who reported that they made little use of distraction-based strategies when experiencing common pains such as a
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headache or stomach ache had better pain outcomes when assigned to the sensory-focussing rather than distraction condition. Older children who reported typically making greater use of distraction-based strategies when experiencing pain showed greater pain tolerance when assigned to the distraction rather than the sensory-focussing condition. There are a number of possible explanations for this pattern of results. First, children who reported that they generally made little use of distraction strategies may not have had as much practice in the use of distraction-based strategies, and hence may have found it more difficult to direct their attention externally, away from the physical sensations. Second, these children may have had a greater tendency and preference to monitor the situation and what they were experiencing in order to maintain a sense of control and equilibrium. Thus, it may have been more difficult for them to imaginatively engage in any ‘‘external’’ story or image. A number of factors related to the selection of participants and experimental pain procedure need to be considered when generalizing the results to pediatric patients experiencing clinical pain. First, the child participants were volunteers informed that they would undergo a painful experience. Hence, children who perceived that they cope poorly with pain or highly anxious children may have declined to participate. Second, study participants were aware that the pain from the cold-pressor task was time-limited and brief. This may have made them less anxious and distressed than would be the case in many clinical contexts. Third, obtaining repeated pain intensity ratings during the cold-pressor task may have made it more difficult for participants in the distraction condition to focus away from the pain. The rating procedure may entail reactive effects of measurement, i.e., changes produced by the measurement procedure itself (von Baeyer, 1994). Hence, the pain outcomes for the distraction group may actually under-estimate the benefits of such an intervention. Nevertheless, the results of the study do suggest that encouraging children to use pain coping strategies involving the manipulation of attention should not be done on a ‘‘one size fits all’’ basis. Distraction-based strategies would appear to be the intervention of choice for younger children and those who employ distraction routinely as a way of coping with pain and stress. Sensoryfocussing, on the other hand, may be helpful for some older children, particularly those children who have little previous experience of distraction strategies. The fact that pain intensity ratings were significantly lower after 1 min in the distraction condition, relative to the sensory-focussing and control conditions, has potential implications for the timing of the onset of distraction interventions. Clearly, it may take children a few minutes to become sufficiently engaged in a distraction image in order to obtain maximal benefit. Further research is needed to assess the generalizability of these findings to clinical contexts. Moreover, a better understanding of the mechanisms by which attentional coping strategies influence children’s pain outcomes is needed in order to understand why particular strategies may be more or less helpful for particular children and in particular contexts.
Acknowledgments The authors are grateful to the staff and students at All Saints Catholic Primary School, All Saints Catholic Girls’ College, and All Saints Catholic Boys’ College in Liverpool, Australia. Thanks also go to Theona Bustos, Anna Cole and Dayna McGill for their assistance with data
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collection. The support of Associate Professor David Champion is also gratefully acknowledged. This work was carried out as part of the first author’s doctoral work at the University of New South Wales, Australia, under the supervision of Drs Brett Hayes and Belinda Goodenough. The first author gratefully acknowledges receiving fellowship support from the Mayday Foundation to participate in the Canadian Institutes of Health Research Strategic Training Program—Pain in Child Health.
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