Attentional bias towards pain-related information diminishes the efficacy of distraction

Distraction is a strategy that is commonly used to cope with pain. Results concerning the efficacy of distraction from both experimental and clinical studies are variable, however, and indicate that its efficacy may depend on particular circumstances. Several models propose that distraction may be less effective for people who display a large attentional bias towards pain-related information. This hypothesis was tested in an experimental context with 53 pain-free volunteers. First, attentional bias towards cues signalling the occurrence of pain (electrocutaneous stimuli) and towards words describing the sensory experience of this painful stimulus was independently assessed by means of 2 behavioural paradigms (respectively, spatial cueing task and dot-probe task). This was followed by a subsequent distraction task during which the efficacy of distraction, by directing attention away from the electrocutaneous stimuli, was tested. In addition, state-trait anxiety, catastrophic thinking, and initial pain intensity were measured. Results indicated that people who display a large attentional bias towards predictive cues of pain or who initially experience the pain as more painful benefit less from distraction on a subsequent test. No effects were found between attentional bias towards pain words, state-trait anxiety, catastrophic thinking, and the efficacy of distraction. Current findings suggest that distraction should not be used as a 'one size fits all' method to control pain, but only under more specific conditions

Detection of tactile change detection on a bodily location where pain is expected

As it is adaptive to accurately detect and localize bodily threats, it has been proposed that the brain prioritizes somatosensory input at body locations where pain is expected. To test this proposition, the detection of tactile changes on a body location was investigated to assess whether detection was facilitated by threat of pain. Healthy participants (N = 47) indicated whether two consecutive patterns of three tactile stimuli were the same or not. Stimuli could be administered at eight possible locations. In half of the trials, the same pattern was presented twice. In the other half, one stimulus location was different between the two displays. To induce bodily threat, a painful stimulus was occasionally administered to the non-dominant lower arm. Mean accuracy of tactile change detection as a function of location was analyzed using repeated-measures analysis of variance (ANOVA). Tactile changes on the threatened arm (i.e., when a tactile stimulus emerged at or disappeared from that arm), both at the exact pain location (lower arm) and at the other location (upper arm), were better detected than tactile changes on other limbs

No pain no gain? Pursuing a competing goal inhibits avoidance behavior

This experiment investigated pain-related avoidance behavior in context of competing goals. Participants (N=56) were presented trials of 2 different tasks of which 1 task could produce pain. They were free to decide whether or not to perform trials of these tasks. In half of the participants, a competing goal was activated by instructing them that they would receive a monetary reward corresponding to the number of pain task trials actually performed (competition group). In the other half of the participants, no competing goal was installed (control group). Results showed that the competition group showed less frequent avoidance behavior than the control group. Furthermore, the association between pain-related avoidance behavior and fear of pain was smaller in the competition group than in the control group. The findings indicate that the emergence of pain-related avoidance behavior depends upon the motivational context, and that the association between pain-related fear and avoidance is not stable. This study has implications for our understanding of disability, and points to the need to consider avoidance behavior within a broad context of multiple, often competing, goals

Phosphate adsorption capacity testing of natural and industrial substrates in view of application in swimming and fish pond water treatment systems

Several substrates have been examined on their phosphate sorption capacity. Wollastonite powder exhibited the highest removal capacity. At all phosphate concentrations (0.1-20mgP/l) the removal was above 82%, with a maximum of almost 96%. The uptake rate was high in the first hour of the batch test and increased with increasing concentration. The wollastonite granules did not take up phosphate at concentrations below 2mgP/l. At higher concentrations the removal fluctuated between 82 and 96%. Slag exhibited a high absorbing capacity (up to 86%) at concentrations starting from 2mgP/l. Other materials (ceramic cylinders with active micro-organisms, porphyry and scoria) that were studied did not exhibit phosphate uptake. From this study it is concluded that, of all the substrates studied, wollastonite powder has the highest phosphate removing capacity. The slag has a lower removal capacity, but is a more coarse material and is thus less prone to clogging. As such it can be concluded that combining both materials, wollastonite powder and slag would be ideally suited for application in a skimmer as the material, provided that the material can easily be replaced