Theories of emotion propose that responses to emotional pictures can occur independently of whether or not people are aware of the picture content. Because evidence from dissociation paradigms is inconclusive, we manipulated picture awareness gradually and studied whether emotional responses varied with degree of awareness. Spider fearful and non-fearful participants viewed pictures of spiders and flowers at four levels of backward masking while electrodermal activity and heart rate were measured continuously. Recognition ratings confirmed that participants’ picture awareness decreased with masking. (...) Critically, effects of spider fear on emotion ratings and heart rate also decreased with masking. These findings suggest that effects of spider fear on emotion ratings and heart rate are closely related to picture awareness. (shrink)

The evolutionary origin of phobias is strongly supported by behavioral genetics and monkey vicarious conditioning data. Prepared Pavlovian conditioning may be only one of the mechanisms mediating the evolutionarily determined outcome in phobias, avoidance. Davey's alternative biased expectancy hypothesis has merit in accounting for some aspects of laboratory data, but it is insufficient to explain the unconscious origin of phobic fear.