Let us consider now some of the consequences of the affect theory for each of the specific primary affects. We shall begin with startle, fear, and interest, which differ, with respect to activation, only in the rate at which stimulation or neural firing increases.

Startle

Startle appears to be activated by a critical rate of increase in the density of neural firing. The difference between startle (or surprise in its weaker form) and interest is a difference in the steepness of the gradient of stimulation. The same stimulus, therefore, may evoke surprise or interest, depending on the steepness of the rise of stimulation (which in turn depends on numerous factors, prominent among which is the degree of unexpectedness). Thus, a gun shot will evoke startle rather than interest. An unexpected tap on the shoulder by someone who is not seen will also evoke startle rather than interest. In the case of the gun shot, the suddenness of increase of stimulation was primarily in the auditory stimulus itself. In the tap on the shoulder the suddenness of this stimulus might have been sufficient, but the overall density of stimulation was so low as to have been insufficient to become conscious in the competition between messages for transformation into reports. We assume that such a weak stimulus must recruit information from memory, which has a steep rate of increase of neural firing to activate a sequence of further, more rapid retrievals which summate to activate startle.