Abstract
Many aspects of mid-level vision appear to operate on the basis of representations which precede identification and recognition, but in which discrete objects are segmented from the background and tracked over time (unlike early sensory representations). It has become increasingly common to discuss such phenomena in terms of ‘object files’ (OFs) — critical mid-level representations which help mediate our conscious perception of persisting objects — e.g. telling us ‘which went where’. Despite the appeal of the OF framework, it remains unclear to what degree OFs underlie consciously perceived object trajectories. Here we present at least one case wherein conscious percepts of ‘which went where’ in dynamic displays diverge from the computation of ‘which went where’ in the OF system. Observers viewed an ambiguous ‘bouncing/streaming’ display in which two identical objects moved such that they could have either streamed past or bounced off each other. We measured two dependent variables: (1) an explicit report of perceived bouncing or streaming; and (2) an implicit object-specific priming (OSP) measure, wherein a ‘preview’ of information on a specific object — e.g. a letter that flashes inside a small box — speeds the recognition of that letter at a later point when it appears again on the same box (compared to when it reappears on a different box). When the displays were manipulated such that observers had a strong bias to perceive streaming (on over 90% of the trials), there was nevertheless a strong *negative* OSP associated with the streaming motion, such that the OSP appeared to have ‘bounced’ even though the percept ‘streamed’. Given that OSP measures have been taken as a hallmark of the operation of object files, this suggests that in at least some cases conscious percepts of ‘which went where’ in dynamic ambiguous displays can override the mapping computed by the object-file system.