Lecture 11: attention and structure in V4; columns in IT

  1. attention

    • Reynolds and Desimone (monkey V2, V4)

    • Connor et al. (monkey V4)

    • Gallant et al. (human V4)

    • Roelfsema et al.; Kanwisher et al.

  2. columns in IT
    • Tanifuji et al.
where is Waldo?

attention and structure in monkey, human V4

the PDF version of the lecture

object-based attention

  1. curve tracing trial sequence

  2. neuron RF on the path between fixation and target

  3. neuron RF off the path between fixation and target

slide 4

factors that determine speed of curve tracing

a classical exploration: 

Minsky, M., with S. A. Papert
Perceptrons
The MIT Press, 1969

several novel algorithms, accompanied by a detailed analysis: 

Edelman, S.,
Line Connectivity Algorithms for an Asynchronous Pyramid Computer
Computer Vision, Graphics and Image Processing, 40:169-187, 1987.

slide 5

object-based attention

slide 6

object-based attention

rate enhancement not cause by fixation behavior:
  1. recordings of eye position during curve tracing

  2. distribution of eye position by stimulus kind

slide 7

object-based attention

simultaneous enhancement of responses to various segments of a single curve

slide 8

object-based attention

response enhancement for curves with and without an intersection

"... neurons that respond to segments of an entire target curve simultaneously exhibit an enhanced firing rate, even if this curve crosses a second, irrelevant curve. This strongly suggests that rate modulations in area V1 provide a correlate of object-based attention. To label responses to one of the curves selectively, the distribution of the rate enhancement should depend on perceptual grouping criteria such as collinearity and connectedness."

slide 9

object-based attention

sample stimuli; in each case, either the face or the base moved back and forth along a fixed axis

slide 10

object-based attention

for each condition, avg signal change across subjects is given for each of three ROIs

GRAY boxes: greater response to the attended attribute compared to the unattended one

BLACK boxes: greater response to the irrelevant attribute of the attended object compared to the unattended attribute of the unattended object (as predicted by object-based theory of attention)

slide 11

object-based attention

"...even though subjects never had to attend to faces or houses in the entire experiment and could not predict which stimulus would move on a given trial, fMRI responses were greater for the task-irrelevant attribute of the attended object than to the relevant attribute of the unattended object..."

slide 12

columns, feature combination in IT

the PDF version of the lecture

slide 13

supplementary material