The recognition of incomplete contour and half-tone figures

The recognition of incomplete figures of everyday objects in fovea and beyond was the aim of
our project. For fifteen subjects with high visual acuity, aged 18 to 24 years, we measured the
necessary minimum of randomly presented parts of the contour. Fixation point was in the centre
of the figure corresponding to the centre of the screen. The figure sizes were varied from 5 min
of arc up to 20 deg by using different viewing distances. The contour minimum for recognition
corresponds to figure size equal to foveola size. Beyond 20 min of arc, up to the resolution limit
of 5 min of arc, recognition decreased linearly. For 0.5 to 5 deg sizes the threshold was relatively
invariant to the size. The psychophysics and event-related potentials were investigated within the
frequency range from 1 to 45 Hz. The relative perceptual availability of global and local features
in sparse patterns was investigated during different stages of learning. Interpolation algorithms
were proposed and tested in additional experiments. We measured the threshold of incomplete
natural half-tone scene recognition. In these experiments, incompleteness was produced with
wavelet transforms. The internal noise limitation of recognition was measured. A match filter
model of the perception of incomplete figures is proposed.

European Conference on Visual Perception.
Budapest, Hungary.
22-26 Aug, 2004.
Supplement. ECVP 2004 Abstract.