What puts the how in where? Tool use and the divided visual streams hypothesis

Area of Science:

• Neuroscience
• Cognitive Psychology
• Visual Perception

Background:

• The dorsal (occipito-parietal) visual stream is theorized to guide actions ('how') separately from the ventral (occipito-temporal) stream for object recognition ('what').
• This theory faces limitations in explaining complex human tool use, which extends beyond simple action guidance.

Purpose of the Study:

• To investigate the neural mechanisms underlying skillful tool use.
• To propose how semantic knowledge influences action representation in the dorsal visual stream.

Main Methods:

• Review of influential theories on visual processing streams.
• Synthesis of functional neuroimaging findings related to object semantics and action representation.
• Theoretical proposal integrating dorsal and ventral stream functions for tool use.

Main Results:

• The dorsal stream alone is insufficient for complex tool use.
• Skillful manipulation of artifacts necessitates access to semantic representations of object functions.
• Functional neuroimaging implicates a left-lateralized network (temporal, frontal, parietal) in representing object semantics.

Conclusions:

• Skillful tool use integrates visual-motor control with semantic knowledge.
• The left hemisphere's dominance in familiar skills may arise from its role in linking semantic information to dorsal stream action organization.
• This integration is crucial for sophisticated artifact manipulation.