6 Functional Specificity & Face Recognition

The Essential Role of the Fusiform Face Area in Facial Recognition

The ability to recognize faces is a complex cognitive process and a major component of human social interaction. The perception of a familiar individual’s identity is dependent on the integration of the person’s facial features which enables us to perceive the face as a whole (LibreTexts, 2021). One region in particular, the fusiform face area (FFA), is located in the right inferior temporal cortex of the fusiform gyrus and is suggested to be a specialized region dedicated to the visual perception of faces (Crump, 2021). More broadly, the FFA is located in the inferotemporal (IT) cortex within the temporal lobe and is activated during the visual recognition process (Koenigshofer, 2022). The FFA is also associated with a broad network for facial processing and recognition in the inferior temporal and lateral occipital cortices (Koenigshofer, 2022).

The Misconception of Functional Specificity and Sufficiency

The name of this specialized brain region, the fusiform face area, has an undertone of functional specificity which implies that this area acts as the “center for facial recognition” and is exclusively engaged in this cognitive process. The notion of sufficiency, which suggests that a single brain region is sufficient for performing a particular cognitive process, also relates to the proclaimed localization of function of the FFA (Kanwisher, 2015). It is commonly misconceived that the FFA is sufficient for conducting facial recognition and that this specific function is localized exclusively to the FFA (Kanwisher, 2015) In reality, no single brain region is ever sufficient for exclusively engaging in a particular cognitive function (Kanwisher, 2015). For example, the occipital face area and the lateral prefrontal cortex are also implicated in face identification in conjunction with the FFA (Pinel & Barnes, 2021).

The Functional Specificity Debate

There is a longstanding debate about the potential determinants of the FFA’s specialization and heightened response to faces. Two opposing hypotheses have emerged: the face specificity hypothesis and the expertise hypothesis. The face specificity hypothesis views the FFA as exclusively a face-specific brain module (Bilalić, 2016). This hypothesis implies that this specialized region is solely involved in the process of detecting and extracting the necessary perceptual information needed to recognize the identity of a person whose face is being visually analyzed (Kanwisher et al, 2006). Furthermore, this theory proclaims that the FFA is distinct from the cognitive machinery initiated during the perception of novel objects (Kanwishner, 2006). This claim is further supported by evidence of greater neuronal activation in the FFA when presenting participants with images of faces in comparison to other non-face stimuli (Crump, 2021).

The opposing expertise hypothesis claims that the FFA is a general visual expertise module that is specialized for distinguishing between individual examples within the same category of stimuli rather than being dedicated exclusively to the visual perception of faces (Bilalić, 2016). Researchers in support of this hypothesis argue that humans are experts of facial recognition due to our extensive recognition experience and exposure to faces in comparison to discriminating among members of other categories (Gauthier et al, 2000). Researchers also argue that faces constitute the category that we encounter the most often in our daily lives. In fact, previous research has found that faces activate the FFA twice as much as stimuli of other categories (Bilalić, 2016).

Although many researchers are in favor of the expertise hypothesis, the determinant of the FFA’s heightened response to faces is still an active area of debate and neither hypothesis is fully established. However, one should be critical of the face specificity hypothesis due to the low likelihood that the FFA is exclusively dedicated to facial processing. Although the concept of functional specificity is appealing and a satisfying explanation of this complex cognitive process, we must be skeptical of this idea since it is highly oversimplified and misrepresents the fundamental way the brain is organized. The brain should not be viewed as compartmentalized with discrete brain regions associated with specific cognitive functions (Kanwisher et al, 2006). The claim that a particular cognitive function can be localized to a specific brain region does not account for the fact that multiple structures are involved in the performance of a single cognitive function. Cognitive processes are far more complex, and the reality is that no single brain region is ever sufficient for exclusively performing a single mental process (Kanwisher, 2015). All functionally specific regions are associated with a broader neural network meaning that there is no functional atlas for different regions of the brain (Kanwisher, 2015).

The Relationship Between Lesion Studies & Functional Segregation

Lesion studies have proven that lesions to particular regions of the brain result in distinct cognitive deficits. For example, bilateral or unilateral right occipito-temporal lesions lead to associated deficits in facial recognition known as prosopagnosia or face blindness (Crump, 2021). This neurological disorder affects visual perception and prevents patients from distinguishing between objects within a single category (Bilalić, 2016). Prosopagnosia particularly affects the identification of familiar faces. Although patients are capable of identifying that the visual stimulus presented to them is a face, they are unable to recognize the identity of the person whose face they are analyzing. In other words, patients are capable of perceiving the individual features of a person’s face but are unable to integrate them into a cohesive, meaningful unit and attribute the features to a specific person (Lim, 2021). In extreme cases of this disorder, some patients are unable to recognize their own face when looking at their reflection in a mirror or at photos of themselves (Lim, 2021).