View from the top: hierarchies and reverse hierarchies in the visual system.

Full Abstract

We propose that explicit vision advances in reverse hierarchical direction, as shown for perceptual learning. Processing along the feedforward hierarchy of areas, leading to increasingly complex representations, is automatic and implicit, while conscious perception begins at the hierarchy's top, gradually returning downward as needed. Thus, our initial conscious percept--vision at a glance--matches a high-level, generalized, categorical scene interpretation, identifying "forest before trees." For later vision with scrutiny, reverse hierarchy routines focus attention to specific, active, low-level units, incorporating into conscious perception detailed information available there. Reverse Hierarchy Theory dissociates between early explicit perception and implicit low-level vision, explaining a variety of phenomena. Feature search "pop-out" is attributed to high areas, where large receptive fields underlie spread attention detecting categorical differences. Search for conjunctions or fine discriminations depends on reentry to low-level specific receptive fields using serial focused attention, consistent with recently reported primary visual cortex effects.

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Author information

Author/s: Hochstein, Shaul (S); Ahissar, Merav (M);

Affiliation: Department of Neurobiology, Neural Computation Center, Hebrew University, Jerusalem, Israel. shaul(-atsign-)vms.huji.ac.il

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Review

Journal: Neuron (Neuron), published in United States. (Language: eng)

Reference: 2002-Dec; vol 36 (issue 5) : pp 791-804

Dates: Created 2002/12/06; Completed 2003/01/16; Revised 2006/11/15;

PMID: 12467584, status: MEDLINE (last retrieval date: 11/6/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Humans
Learning - physiology
Neurons - physiology
Neuropsychological Tests

Pattern Recognition, Visual
Vision - physiology
Visual Cortex - cytology; physiology
Visual Perception - physiology

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