Winning or not losing? The impact of non-pain goal focus on attentional bias to learned pain signals.

TL;DR: This experiment aimed to replicate the finding that attentional bias for pain signals in healthy participants can be reduced when a non-pain goal is pursued, and to extend this finding by taking into account the outcome focus of the non- pain goal.

About: This article is published in Scandinavian Journal of Pain.The article was published on 2018-10-25 and is currently open access. It has received 5 citations till now. The article focuses on the topics: Attentional bias & Cognitive bias.

Summary

Introduction

• Insights into the precise nature of cognitive bias, including attentional bias to threat signals, are considered pivotal to understanding pain and related distress, also known as Background and aims.
• In healthy participants, attentional bias for pain signals can be reduced when a non-pain goal is pursued, and (ii) to extend this finding by taking into account the outcome focus of the non-pain goal.the authors.
• The pattern of results suggests that this effect was indeed reduced in the goal groups as compared to the control group, but there was no significant group difference.
• The motivational perspective suggests that attentional bias varies with the goals that people pursue [34,45].
• Similarly, individuals may be more motivated to pursue non-pain prevention goals than non-pain promotion goals.

2. Methods

• 1. Participants advertisements at campus, participated in this experiment, with 36 participants assigned to each of the three study groups (promotion goal group, prevention goal group, and control group; see Section 2.2.4.).
• For safety reasons, pregnant women and people with an electronic implant such as a cardiac pacemaker were excluded as they should not be exposed to the electrocutaneous stimulation.
• All participants were fluent in Dutch, gave written informed consent and received 10€ compensation for their participation, paid in the form of vouchers.
• Characteristics of the final sample included for analysis are reported in the Results Section.
• The study was approved by the Ethics Committee of the Faculty of Psychology and Neuroscience at Maastricht University (Reg. nr. 74_5-10-2008-2).

2.2.1. Electrocutaneous stimuli

• Electrocutaneous stimuli (300-millisecond duration; bipolar sinus waveform; 50 Hz) were delivered by an isolated bipolar constant current stimulator (DS5; Digitimer Ltd, Hertfordshire, United Kingdom).
• These stimuli were applied to the left ankle (external side) using two 8-mm stainless steel surface electrodes, vertically placed with 1-cm inter-electrode distance, secured to the participant's skin by adhesive collars, and filled with microlyte electrode gel.
• Unpleasant and demanding some effort to tolerate [35,41,46].
• Stimulus intensity was increased until the participant rated the stimulus as a 9.
• Participants were not informed about these procedural details.

2.2.2. Spatial cueing task

• Spatial cueing tasks have been successfully used as a methodology to assess attentional bias to pain signals [35,41,42,43,46].
• Participants were encouraged to maintain central fixation consistently.
• Thirty ms after cue offset, a small target (‘/’or ‘\’; 4 mm) appeared at the centre of either the left or the right frame, either at the position previously occupied by the spatial cue (valid trials) or at the other position (invalid trials).
• Targets remained on the screen until a response was made or for max.
• Each cue colour appeared equally often (at either position) and was equally often followed by each target identity.

2.2.3. Differential conditioning

• A differential conditioning procedure was used to create pain cues that were sometimes followed by painful stimulation and no-pain cues that were never followed by painful stimulation [35,41,42,43,46].
• In the test phase (see Section 2.3.4.), one of the cue colours (pink or green; counterbalanced between participants) was immediately followed by the unpleasant electrocutaneous stimulus on one-third of the trials in which it appeared (pain cue).
• The other colour was never followed by electrocutaneous stimulation (no-pain cue).
• Larger cue validity effects for pain cues than for no-pain cues were taken to reflect biases in attention to pain signals [14,43].

2.2.4. Non-pain goal task and goal focus instructions

• This study included two goal groups, who performed the same non-pain goal task but with a different goal focus.
• The non-pain goal task consisted of digit trials that were similar to the cueing task trials (see Section 2.2.2.), except that a random digit from 1 to 9 (black; 7 mm) replaced the fixation cross for 50 ms during the inter-trial interval or during the trial (but not simultaneously with targets or responses to targets, for technical reasons).
• Participants in both goal groups received 10€ at the start of the session and were led to believe that the monetary compensation for their participation at the end of the session would depend on digit naming performance (i.e., end score on the non-pain goal task, at the end of the test phase; see Section 2.3.4.).
• It was explained that one would get one point for each fast and accurate response, but lose one point for each slow, inaccurate, or missed response.
• Intermediate scores were provided during regular task breaks (see Section 2.3.).

2.2.5. Apparatus

• In the goal groups, verbal response latency was registered via a Sennheiser HMD/HME 25-1 (Sennheiser Electronic Corporation, Old Lyme, CT, USA) microphone/headphone combination connected to a voice key.
• Self-report questions and questionnaires were completed via a secure online survey system (EMIUM ; Research Institute Experimental Psychopathology, Maastricht University, the Netherlands).

2.3. Procedure

• Participants were tested individually in a dimly lit, quiet testing room in the department of Clinical Psychological Science at Maastricht University.
• During the lab session, the participants did not drink or eat anything containing caffeine or other stimulants (e.g. coffee, tea and chocolate).
• They received debriefing about the actual purpose and procedures of the experiment after all participants had completed the study.
• Then they completed the 13- item Pain Catastrophizing Scale [39], the most commonly used questionnaire measure of pain catastrophizing [51].
• The goal groups were instructed to respond manually to targets (‘/’or ‘\’) on every trial and verbally to digits that appeared on 25% of the trials; the control group had only to respond to targets.

2.3.1. Practice phase

• The goal groups practiced first the cueing task without the digit naming task (32 cueing task trials), then in combination with the digit naming task (16 cueing task trials intermixed with 16 digit trials).
• The control group practiced the cueing task only without the digit naming task (2 x [16 cueing task trials intermixed with 16 digit trials]).
• Participants received no electrocutaneous stimulation and were informed about this.
• Following practice, all participants assigned to the goal groups were able to repeat the rules for gaining/losing points and money.

2.3.2. Baseline phase

• For all groups, the baseline phase consisted of 96 cueing task trials intermixed with 32 digit trials.
• The goal groups performed the cueing task in combination with the digit naming task, whereas the control group performed only the cueing task.
• Participants received no electrocutaneous stimulation and were informed about this.
• 3.3. Acquisition phase break) followed by the test phase.
• On 4 trials, the spatial cue was a pain cue, followed by electrocutaneous stimulation; on the other 4 trials, the spatial cue was a no-pain cue.

2.3.4. Test phase

• The test phase consisted of 144 cueing task trials intermixed with 48 digit trials.
• On one-third of the trials in which a pain cue appeared (24 cueing task trials; 8 digit trials), participants received electrocutaneous stimulation.
• On the other trials, no electrocutaneous stimuli were delivered.
• During all phases, incorrect and premature responses to targets (‘/’or ‘\’) were signalled by a short beep along with the display of an error message at screen centre for 500 ms (+ 1000 ms pause).
• Every 32 trials, feedback about target responses (i.e., mean reaction time; number incorrect) and digitnaming performance (i.e., intermediate score on goal task; goal groups only) was presented at screen centre during short breaks terminated by the participant.

2.3.5. End of session

• All ratings were made on 11-point numeric rating scales with end points labelled 0 (not at all) and 10 (to a very large extent or extremely).
• An index of promotion goal strength strength is created by averaging all items relevant to prevention goals [26].
• The participants also completed the Fear of Pain Questionnaire [28,33], the BIS/BAS Scales [3,15], and the Goal Pursuit Questionnaire [24].
• All questions and questionnaires appeared on the computer screen and participants answered by using a keyboard and computer mouse.

2.4. Experimental design and data analysis

• This experiment employed a 2 (valid cueing vs. invalid cueing) x 2 (pain cue vs. no- pain cue) x 3 (promotion goal group vs. prevention goal group vs. control group) factorial design with reaction time (RT) to targets as main dependent variable.
• This design was used to examine group differences in attentional bias for pain cues during the test phase and to check for attentional bias for one of the cues as a function of its distinctive visual features rather than its conditioned signal value during the baseline phase (prior to differential conditioning in the test phase).
• The reported RT analyses were based on median correct RTs to reduce the impact of outliers, but the same pattern of results was obtained with mean correct RTs (also when responses deviating more than 2.5 SDs from the mean latency per condition were discarded).
• The sample size was informed by previous findings in this field.

3.1. Group characteristics

• Six participants were excluded from the analyses: four because of incomplete (computer task) data; two because of meeting exclusion criteria (see Section 2.1.).
• The final groups did not significantly differ in gender ratio, χ2 (2, N = 93) = 1.7, p = .4, mean age, fatigue at the start of the lab session, pain catastrophizing, or electrocutaneous stimulus perception (Table 1).
• That is, and as can been seen in Table 1, electrocutaneous stimulation was more often expected after pain cues than after no-pain cues, and participants were more fearful when pain cues were presented than when no-pain cues were presented, with no differences between groups.
• They are included in the reported analyses.
• In the lab situation, groups did not differ in self-reported focus or motivation (Table 2), except for motivation to perform the target classification task well.

3.2.1. Baseline phase

• Median correct RTs on cueing task trials (Table 3) were subjected to an ANOVA with cue validity, cue identity, and group as factors.
• There were no other significant results from the ANOVA.

3.2.2. Test phase

• Median correct RTs on cueing task trials (Table 3) were subjected to an ANOVA with cue validity, cue identity, and group as factors.
• There were no other significant results from the ANOVA.
• The authors sample of 93 provided good statistical power to detect a large-sized difference between the three groups in attentional bias, but the study was underpowered to detect a small-to-medium-sized group difference (30.0% for ηp2 = .03).
• So, smaller effects may exist that were not captured.

4. Discussion

• The current experiment was designed to test (i) whether attentional bias to learned pain signals is reduced with non-pain goal pursuit and (ii) whether this reduction is stronger with non-pain prevention focus than with non-pain promotion focus.
• This crucial difference in goal focus instructions with the original study [35] might explain differences in findings.