Expectations about future motions can influence both perceptual
judgements and pursuit eye movements. However, it is not known
whether these two effects are due to shared processing, or to
separate mechanisms with similar properties. We have addressed
this question by providing subjects with prior information about
the likely direction of motion in an upcoming random-dot motion
display and measuring both the perceptual judgements and pursuit
eye movements elicited by the stimulus. We quantified the
subjects' responses by computing oculometric curves from
their pursuit eye movements and psychometric curves from their
perceptual decisions. Our results show that directional cues
caused similar shifts in both the oculometric and psychometric
curves toward the expected motion direction, with little change
in the shapes of the curves. Prior information therefore biased
the outcome of both eye movement and perceptual decisions without
systematically changing their thresholds. We also found that
eye movement and perceptual decisions tended to be the same
on a trial-by-trial basis, at a higher frequency than would
be expected by chance. Furthermore, the effects of prior
information were evident during pursuit initiation, as well
as during pursuit maintenance, indicating that prior information
likely influenced the early processing of visual motion. We
conclude that, in our experiments, expectations caused similar
effects on both pursuit and perception by altering the activity
of visual motion detectors that are read out by both the oculomotor
and perceptual systems. Applying cognitive factors such as
expectations at relatively early stages of visual processing
could act to coordinate the metrics of eye movements with
perceptual judgements.