Bernal S D_2010.pdf - University of Plymouth

2.1. OBJECT RECOGNmON
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Figure 2.4.- Schematic representation of the HMAX niottcl (right) with tentative mapping over
the ventrul stream in the primate visual corlex (left). Tlic model attempts to reproduce
activity and funciiimality nhserved along the ventral visual pathway, comprising
areas Vi, V2, V4 and IT. The model is based upon widely accepted basic
principles such as the hierarchical arrangement of these areas, with a progressive
increase in receptive held size and complexity of preferred stimuli, as well as a
gradual build-up of invariance to position and scale as we move further up the hierarchy.
Two operations are performed in alternating layers of (he hierarchy; the
invariance operation (the max function over a set of alTerents selective to the same
feature) whicli occurs lietween layers of the same level .e.g. fromSl toCI (dotted
circles and arrows); and the selectivity operation (a template-matching operation
over a set of afferents luned to different features) implemented between layers of
dilferent levels, e.g. from CI to S2 (plain circles and arrows). The main route to
[T is denoted with black arrows, and the bypass route is denoted with blue arrows.
Colours indicate the correspondence between model layers and cortical areas. The
table (right) provides a summary of the main properties of the units at ihe differenl
levels of the model (Serrc et al, 2007b).
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