INB-Lunch-Seminar

Human overt attention under natural conditions

Peter König

Humans make billions of eye movements in their lifetime, yet our
knowledge of the principles governing the selection of fixation points
is surprisingly limited. Here we investigate the contribution of
stimulus dependent factors, task context and spatial constrains. We
presented natural scenes, partly combined with auditory stimuli, to
human subjects in a variety of conditions and measure subjects'
eye-movements. We find that (1) selected fixation points are
systematically correlated to many low-level visual features; (2) the
empirical saliency is combined linearly; (3) yet the influence of the
task context and spatial constraints are systematically stronger than
that of low level stimulus properties; (4) specifically the task context
does not act by modulating the influence of low level features (strong
top-down) and the difference between total and partial correlation is
small; (5) presenting ambiguous stimuli we can demonstrate that action
precedes perception; (6) building on a large set of low level features,
mid level features and spatial constraints fixations can be predicted
with near inter subject reliability (ROC > 0.75) (7) a first
investigation with a set of canonical features gives promising results
and the QR model integrating the experimental results is introduced.