Figure 1.

Hypothetical psychometric function from a temporal order judgement (TOJ) experiment. Two stimuli (A and B) are presented with a range of stimulus onset asynchronies (SOA). Subject's probability of reporting stimulus A appearing first is plotted as a function of SOA, defined as ‘stimulus A lead time’. SOA is positive when stimulus A is presented first and negative when stimulus B is presented first. The single-headed arrow (green) corresponds to the point of subjective simultaneity (PSS), the SOA that corresponds to 50% on the ordinate. The double-headed arrow (blue) indicates the just notable difference (JND), defined as half of the interquartile range. (Online version in colour.)