|
Abstract
|
We have noted several characteristics of the phenomenon. It seems to be easier to observe: (i) with highly familiar faces; (ii) when centred at the blind spot; (iii) with achromatic stimuli; (iv) with faces varying in size from 7 cm to about 14 cm; and (v) with medium-contrast levels. It often occurs in bursts, generally very fast, may encompass an emotional response, may involve a number of unrecognised faces, and generally tends to take at least 20 ^ 60 s to start for subjects observing it for the first time. Further, it seems to be more specific to human faces as compared to monkey faces. It can be triggered by small eye movements.
The multiple-faces phenomenon appears to be related to adaptation to a very familiar face; as adaptation occurs, other face-related stored information is displayed by visual memory (overlaying the priming face). Such mechanism initially seems to act locally, as for eyes, mouth, nose, moustache, etc [more related to our category (iii)], and later, globally, as for whole faces, hair, beard, etc [more related to our category (iv)]. We have not found in the literature studies on face adaptation, however.
We base our main hypothesis on physiological studies that identified cells responsive to faces, profile, and elements of a face in monkeys' inferotemporal cortex (for a review, see Desimone 1991). We suppose that mechanisms for detecting and identifying faces exist, and that these are primarily tuned in very early infancy to faces more frequently viewed (ie generally the mother's or first care-giver's face) and that later, as other faces are detected and stored, this mechanism builds upon previously stored most (similar?) seen faces, or opens new categorical face matrices. It is interesting to observe that male faces can be seen in female's photos and vice-versa. We are still gathering addi- tional and more controlled data to learn more about the occurrence and characteristics of this phenomenon.
Language: en |