Reading trustworthiness in faces without recognizing faces.

We show that developmental prosopagnosics with severe impairments in both memory for faces and perception of facial identity can make normal trustworthiness judgements of novel faces. We tested four prosopagnosics on three different face sets. The first set consisted of faces that varied on multiple dimensions and that have been used to demonstrate impairments in trustworthiness judgements of patients with bilateral amygdala damage. The second and third sets consisted of standardized faces with direct gaze, neutral expression, and similar age. On all tests, two prosopagnosics made judgements that closely agreed with control judgements while the other two showed weak agreement but within the normal range. The performance of the tests was correlated suggesting that the tests mapped the same underlying judgement irrespective of the specific face stimuli. The normal performance of two of the prosopagnosics suggests that forming person impressions from faces involves mechanisms functionally independent of mechanisms for encoding the identity of faces.