The CRIP effect: How central distractors effect phenomenal appearance, sensitivity, and confidence in periphery.

Oriented lines in the centre of a pattern affect discrimination, but not detection, of lines in the periphery (Central Region Interference with Periphery, CRIP effect). Surprisingly, sensitivity is higher when centre and periphery have opposite orientation (Oletto et al., 2025). In a new series of experiments, we used full-screen patterns composed by diagonal (+45° vs -45°) oriented lines. In the centre and in the periphery the orientation could be congruent or incongruent. Between centre and periphery there was a gap, which was varied in size: 2° and 6°. In comparison with a baseline without distractors performance decreased, confirming the CRIP effect. This effect is modulated by gap size and confidence. In terms of subjective reports there was a bias towards reporting opposite orientation with respect to the centre. This result illustrates an important difference between CRIP effect and crowding and between CRIP effect and extrapolation and filling in processes: the CRIP effect is related to global rather than local interactions. In conditions of uncertainty, which is characteristic of peripheral vision, people do not simply report properties of what is in the central region.