1. Ahissar, Hochstein (1997) Nature Task difficulty and specificity of perceptual learning 1 st third 2nd third Final session Task difficulty Stimulus-to-mask onset asynchrony

2. Easy task: Learning was general, Complete transfer when swapping -> position non-specific

4. Classical view of visual hierarchy: 1.Complexity of receptive field - hierarchical 2.Parallel stream – dorsal vs ventral 3.Learning (experience)-, attention (context)- dependent processing (feedback) only at higher areas, but recently down to V1

6. Rapid, generalized perception “ vision at a glance ” Slow detailed perception “ vision with scrutiny ” Automatic, implicit Categorical scene interpretation : pop-out Conscious, attentive Attention to details Learning effect transferCondition-specific Feedforward processing Hierarchical Feedback processing Reverse hierarchical Reverse Hierarchy Theory of Visual Perception Two modes of perception Reverse hierarchy theory 1 2 3

7. Common view: Vision at a glance – effortless simple feature detection - low-level mechanism Vision with scrutiny – high-level Pop-out for complex feature (shading, etc) challenge this idea Reverse Hierarchy Theory: Vision at a glance – initial, crude, global percept, e.g., pop-out – high-level cortical mechanism - early spread attention – large receptive field Vision with scrutiny – focused attention, low-level - when focused attention, inattentional blindness

8. Early spread attention, high cortical level determination of initial conscious perception

9. Change blindness Initial conscious perception acquire gist of scene. Later focused attention grasps low-level detail. Vision at a glance vs vision w/ scrutiny

10. Pop-out for complex features Problem: what is high and low level?

11. Problems Reverse Hierarchy Theory: 1.Hierarchy is poorly defined from connection pattern. Low-level vs high-level Pop-out with shading may be still low-level. 2.Sharp tuning for feature/space is not necessarily mean superior discrimination. See population coding. 3. Attention effects with large receptive fields - Desimone

12. by M. Sereno Perception – parallel processing

13. Two streams of visual processing

15. Neural activity in early visual cortex reflects behavioral experience and higher-order perceptual saliency Nature Neuroscience (2002)

16. Top-down reentry of later involvement of low-level area