The reversal of perceptual and motor compatibility effects differs qualitatively between metacontrast and random-line masks.

In masked priming tasks, participants typically respond faster to compatible than to incompatible primes, an effect that has been dubbed as the positive compatibility effect (PCE). However, when the interval between the prime and the mask is relatively long, responses are faster to incompatible than to compatible primes. This inversion is called the negative compatibility effect (NCE). Two main origins of the NCE have been proposed. The object-updating theory holds that when the masks share stimulus features with the primes, both perceptual and motor processes generate an NCE. As an example, for masks composed of overlaid left and right prime arrows, the NCE is thought to be positive priming induced by the arrow of the mask pointing in the opposite direction of the prime. In contrast, the motor inhibition theories hold that the origin of the NCE is purely motor and can be demonstrated when masks do not share features with primes. To test both hypotheses, the present study aims at delineating the respective contributions of perceptual and motor components of the NCE in the context of different types of masks. Consistent with the object-updating hypothesis, we found both perceptual and motor NCEs at the long SOA with metacontrast masks (with internal contours corresponding to left and right overlaid arrows). Consistent with the motor inhibition hypothesis, we found motor NCE but no perceptual NCE at the long SOA with random-line masks (containing no prime features). The study thus suggests that the origin of the NCE depends on the type of mask.