The (shared) features of fear: Toward the source of human fear responding.

Little is known about why people behave the way they do in threatening situations. Some theories invoke a transfer of responses from unconditioned stimuli (US) to conditioned stimuli (CS), but this principle goes astray because responses to the US and CS can differ substantially. The idea that we introduce here is that the pattern of responses to a newly established CS does not come from the US but (at least partly) transfers from how one (learned to) respond(s) to previously encountered stimuli with threat value. So, we conceptualize threat value as a stimulus feature that allows responses to transfer between stimuli that share this feature (in the same way as, for example, overlap in color or shape can support transfer). In contrast to prevailing views, this new perspective focuses on the relation between the CS and already established threat signals rather than on the relation between the CS and the US. We discuss how this shared features perspective on human fear responding can inspire future directions in both the laboratory and clinical practice.