Expectation of pain replicates the effect of pain in a hand laterality recogniti

[Guest guest]

Eur J Pain. 2006 Apr;10(3):219-24.

Expectation of pain replicates the effect of pain in a hand

laterality recognition task: Bias in information processing toward

the painful side?

Hudson ML, McCormick K, Zalucki N, Moseley GL.

Department of Physiotherapy, The University of Queensland & School of

Physiotherapy, The University of Sydney, P.O. Box 170, Lidcombe, NSW

1825, Australia.

BACKGROUND: People in pain, or expecting pain, sometimes bias their

attention towards pain-relevant cues. Perhaps they also bias their

attention towards the body part in question.

AIM: To determine if experimentally induced pain, and the expectation

of pain, involve an information processing bias towards the hand in

question.

METHODS: Seventeen asymptomatic subjects performed a hand laterality

recognition task during three conditions: control, during hand pain

induced by intramuscular injection of hypertonic saline (pain), and

during expectation of hand pain, induced by isotonic saline injection

(expectation). Mean response time (RT) was determined for three 45 s

epochs within each condition and RT was compared between hands,

conditions and epochs using a 2x3x3 repeated measures multivariate

analysis of variance.

RESULTS: There was a handxcondition interaction and a

handxconditionxepoch interaction (p<0.05 for both). RT to recognise

the opposite hand was approximately 600ms longer during epochs when

subjects were in pain or expected pain than during control trials.

During those epochs, RT to recognise the opposite hand was

approximately 600ms longer than RT to recognise the injected hand,

which was consistent across conditions and across epochs.

CONCLUSIONS: Both pain and the expectation of pain increased RT to

recognise the opposite hand. The findings are consistent with a bias

in information processing toward the painful or impending painful

hand.