Perception and Attention - Computational Explorations in Cognitive Neuroscience - page 268

from V2 , V4 ,to IT . A model of this pathway devel-
oped spatially invariant representations that collapse
across differences in spatial location and size, while re-
taining the distinctions between different objects. These
representations formed gradually over sequential layers
of processing. The network generalized the invariance
transformation, learning about novel objects in a subset
of locations and sizes and recognizing them in a large
number of novel locations and sizes.
The other major visual processing pathway is the
spatial or “where” pathway in the dorsal stream of
processing in the parietal cortex. We explored the abil-
ity of this pathway to influence the allocation of atten-
tion to spatial locations. Spatial attention can interact
with and facilitate processing in the object recognition
pathway, enabling multiple objects to be processed by
sequentially focusing attention to these objects. We also
explored spatial attention in the Posner spatial cuing
task. Our lesioned model simulated the performance
of neglect patients (with lesions in one parietal hemi-
sphere), who exhibit slowed processing of targets rep-
resented in the lesioned hemisphere.

8.8 Further Reading

Mozer and Sitton (1998) presents a comprehensive
treatment of many different attentional (and object
recognition) phenomena using many of the same com-
putational principles employed in the models described
in this chapter.
For a comprehensive and influential discussion of at-
tention, see Desimone and Duncan (1995).
Behrmann and Tipper (1994) discuss many of the
phenomena from neuropsychological studies of neglect.
Farah (1990) gives a compact treatment of higher-
level vision from a neuropsychological perspective, and
her new topic is also good (Farah, 1999).
The following are some particularly useful papers
on the neural basis of object recognition and visual
processing more generally: Desimone and Ungerlei-
der (1989); Ungerleider and Haxby (1994); Goodale
and Milner (1992); Tootell, Dale, Sereno, and Malach
(1996);

Logothetis and Sheinberg (1996); Tanaka

(1996).