Role Of Face-Selective Cells In Visual Perception
Face selective cells (in macaque inferotemporal “face patches”) play a two stage, time evolving role in visual perception: ==they first support rapid face detection and then support fine grained discrimination/identif...
Face selective cells (in macaque inferotemporal “face patches”) play a two stage, time evolving role in visual perception: ==they first support rapid face detection and then support fine grained discrimination/identification of individual faces==.[:cite[1]{ln=2}], [:cite[2]{ln=4}] 1) Early role: fast face detection using an object general code ==At short latencies, face selective cells initially adopt a “general code optimized for face detection.”==[:cite[1]{ln=4}] In this early phase, ==face cells encode stimuli “using a shared axis for both faces and objects,” oriented toward faces in a DNN derived feature space, which is described as “optimally subserving face detection.”==[:cite[2]{ln=5}] This matches the idea that visual processing can begin with broad category detection before detailed analysis.[:cite[1]{ln=2}], [:cite[3]{ln=5}] 2) Rapid switch: stimulus gated change in coding within 20 ms ==After a rapid, concerted population event lasting <20 ms, the neural code “transformed into a face specific one.”==[:cite[1]{ln=5}], [:cite[2]{ln=2}] ==This switch is “stimulus gated”: it occurs only for faces, while non face objects continue to evoke responses along fixed object axes.==[:cite[4]{ln=5}], [:cite[1]{ln=6}] 3) Later role: face specific discrimination (identity/feature encoding) In the later phase, ==new tuning emerges for multiple higher dimensional face features that “support fine face discrimination,”==[:cite[1]{ln=5}] and ==the population “switches to new axes selectively for faces to optimally distinguish face identities.”==[:cite[2]{ln=6}] The paper further states that the transition is marked by ==(i) reversal of the face axis in low dimensions, (ii) sparser responses, and (iii) emergence of tuning to new facial feature dimensions that improve discrimination between individual faces.==[:cite[2]{ln=7}] Consistent with this, ==the authors conclude that face cells “transition from detection to discrimination by switching from an object general code to a face specific one.”==[:cite[1]{ln=7}] Bottom line ==Face selective cells contribute to visual perception by implementing a dynamic “detect then discriminate” computation for faces: early activity favors detecting that something is a face, and later activity reorganizes into a face specific code that better encodes identity relevant facial features.==[:cite[1]{ln=2}], [:cite[1]{ln=4}], [:cite[1]{ln=5}], [:cite[2]{ln=4}], [:cite[2]{ln=6}]