Trevor J Hine, John Van Beusekom

Purpose:
LeDoux proposed that threatening visualstimuli are rapidly processed unconsciously throughthe amygdala and its associated pathway. We pre-sented both verbal and pictorial spider and neutralcontent to both a control group and an arachnophobicgroup without their awareness in order to assess dif-ferences in emotional responding.

Method:
Continuous flash suppression (CFS) pro-duces prolonged periods of suppression of an image inone eye when the other eye is viewing a rapidlychanging (10 Hz), complex coloured mask. A mirrorhaploscope was used to enable CFS presentation(seven seconds) of images of spiders, spider words(e.g. WEB), neutral images (e.g. a baby seal) andneutral words (e.g. TUB) to the two groups (eachn = 15). Frequency of image break-through into con-sciousness were measured, as was ‘guesses’ of theemotional valence of the suppressed image along withratings of a neutral face as either friendly or hostile.

Results:
Spider images broke through more oftenthan neutral images. When the stimulus was notconsciously processed, d’ analysis showed that thearchnophobic group was more accurate in guessingthe valence of the stimulus than the controls. Finally,the arachnophobic group rated the faces to be morehostile when primed by spider related content than thecontrol group.

Conclusion:
We provide behavioural evidence fora functional but unconscious ‘low-road’ visualpathway in humans that is more active for spider thanneutral stimuli, especially in arachnophobics. Furtherrefinements of the CFS technique are suggested toimprove its efficacy in tapping unconscious emotionalresponses.