Perceptual amplification following sustained attention: implications for hypervigilance.

It is known that attending to a cutaneous stimulus briefly increases its subjective intensity. The purpose of the present study was to determine whether an extended period of attention would produce a longer-lasting perceptual amplification. Eighty subjects were assigned alternately to experimental and control groups. Members of the two groups received identical series of tactile stimuli (near-threshold von Frey filaments applied to the forearm), but those in the experimental group carried out a two-interval forced-choice detection task that required attention to the filaments, while subjects in the control group attended instead to a video game. After this initial phase, all subjects gave magnitude estimates of the intensity of a wide range of von Frey filaments. The experimental group gave estimates 42% greater than those of the control group, both for filaments used in the initial phase, and others not presented previously; the perceptual amplification did not, however, transfer to a different type of pressure stimulus, a 5 mm-diameter rod applied to the skin. The aftereffect of sustained attention lasted for at least 15 min. This phenomenon, demonstrated in normal subjects, may have implications for the hypervigilance of some chronic pain patients, which is characterized by both heightened attention to pain and long-lasting perceptual amplification of noxious stimuli.