The detection of temporally defined objects does not require focused attention

Long-term Object Discrimination at Several Viewpoints Develops Neural Substrates of View-invariant Object Recognition in Inferotemporal Cortex

Object recognition requires differentiation across different objects and generalization across views of the same object. We previously demonstrated that discrimination of object images at several views without any possibility of association was enough to achieve object recognition within a certain range of viewing angles and confirmed the response tolerance of monkey inferotemporal cells within a similar range of viewing angles. However, neither behavioral object recognition nor electrophysiological response tolerance was complete across views. In the present study, we extended such learning past performance saturation and recorded neuronal activity during the further learning period. When monkeys were trained to discriminate objects at several views, we found that they could discriminate the trained objects regardless of the eventual change in viewing angle, and confirmed a response tolerance at the population level over a large viewing angle range covering all the viewpoints experienced. At the cell population level, such overtraining leads to significantly higher neural response similarity for views of the same objects than for views of different objects regardless of the extent of viewing angle separation. These results suggest a possible method of view-invariant object recognition development.

Interaction of attention and temporal object priming

Within a 3 x 3 matrix of 90 degrees corner junctions, detection of a Kanizsa-type square is facilitated when the target display is preceded by a 40-Hz flickering premask of 3 x 3 crosses, with four crosses synchronously oscillating at the subsequent target location. To examine whether this 'synchrony-priming' effect is influenced by, or dependent on, visuo-spatial attention, a spatial-cueing manipulation was introduced. Observers were presented with a visual or acoustic cue which indicated the likely target quadrant. The main finding was that synchrony priming was larger for invalidly, compared with validly, cued locations, and that the priming effect was figural, rather than spatial, in nature (i.e., confined to points associated with the completed boundary, rather than extending to the inner region, defined by the synchronous premask elements). This pattern of effects argues that target processing is expedited not by attracting spatial attention to the primed location, but by the prime expediting (figure-specific) target encoding, as a result of which the target position gains a processing and selection advantage relative to non-primed locations.