An ocular motor index of rapid face recognition: The 'looking-at-nothing' effect

In the looking at nothing effect, subjects performing a task involving stimuli that are no longer visible tend to fixate the regions on an empty screen where those stimuli had been located. We performed three experiments to examine whether this effect could serve as an index of short-term face recognition. Subjects saw a short video of a person's face and then saw briefly a choice screen of four faces, followed by a screen with empty boxes, after which they responded whether the learned face was one of the four. Fixations made while the screen without faces was present were more likely to be directed towards the target face when it had been shown, and this was the case not only on hit trails, but also on miss trials. Examining fixations made during a 3-second window showed that this looking at nothing effect was present for the first fixation only, after which subjects were more likely to fixate the other empty boxes, a 'looking away from nothing' effect. Including data from all three experiments showed an age-related decline in discriminative sensitivity but not in the looking at nothing effect. However, there was a positive correlation between discriminative sensitivity and the looking at nothing effect. We conclude that the looking at nothing effect can index rapid face recognition, that it is related to explicit discriminative performance, and that its short-term dynamics bear similarities to inhibition of return.