Macaque monkey psychophysics supporting the continuity illusion. (A) the two rows show the two different possible stimulus configurations in the task. In the column, the first set of sounds are always complete, when the second sound has a gap, the macaques must release the lever for a reward. When the second sound is continuous the monkey must not release the lever for reward (otherwise a false alarm, FA, is registered and no reward is given). In total there are four possible responses; two correct and two incorrect for each of these two types of trials. Importantly, the noise is irrelevant because it is the same and equally present in both of the sounds that are heard and the animals are strongly encouraged to detect the discontinuous sound. (B) The different signals used in Petkov et al. (2003) (C) Monkey performance for the two different stimuli for interrupting noise (circles) and surrounding noise (triangles). Hits and false alarms map onto the different conditions shown in (A). See the text for details.