Covert facial recognition

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Covert facial recognition is the unconscious recognition of familiar faces by people with prosopagnosia. The individuals who express this phenomenon are unaware that they are recognizing the faces of people they have seen before. [1]

Contents

Joachim Bodamer created the term prosopagnosia in 1947. Individuals with this disorder do not have the ability to overtly recognize faces, but discoveries have been made showing that people with this disorder have the ability to covertly recognize faces.

There are two types of prosopagnosia, congenital and acquired. Congenital prosopagnosia is an inability to recognize faces without a history of brain damage; while acquired prosopagnosia is caused by damage to the right occipital-temporal region of the brain. In the 1950s it was theorized that the right cerebral hemisphere was involved in facial recognition and in the 1960s this theory was supported by many experiments. [2]

Although the ability for overt facial recognition is inhibited in patients with prosopagnosia, there have been many studies done which show that some of these individuals may have the ability to recognize familiar faces covertly. These experiments have used behavioral and physiological measures in order to demonstrate covert facial recognition. A common physiological measure that is used is the measure of autonomic activity by using skin-conductance responses (SCR) which show a larger response in individuals with prosopagnosia who are shown pictures of familiar faces compared to pictures of unfamiliar faces. [2]

Theories and reasoning

Many theories reside in the topic of cognitive facial recognition. First, the theory of contradiction between prosopagnosia and covert recognition. Prosopagnosia is the inability to recognize faces but is believed to stem from damage to the ventral route of the visual system. Whereas covert recognition is shown in people that lost their ability to recognize faces, implying an intact ventral limbic structure projecting to the amygdala. [3]

Theory two states that it cannot be observed in developmental cases of prosopagnosia, which was proposed by Grueter. Developmental prosopagnosia is a severe face processing impairment without brain damage and visual or thinking dysfunction but can sometimes run in families (some indications that there may be a genetic reason for the disorder). This theory is thought to rely on the activation of face representations created during the time of normal processing. [4]

Contradicting the last theory, the affective valence in developmental prosopagnosia theory states that individuals may be processing faces on affective dimensions, feelings and emotions, rather than familiarity dimensions, previous occasions and when they met. [3]

Next is the dual-route models theory, proposed by Bauer, and states covert recognition can be seen in people that endured a time of normal face processing before actually getting the condition. With this, there are two different types of covert recognition: behavioral and physiological. Behavioral covert recognition is measured by reaction time and occurs within a cognitive pathway consisting of face recognition units (FRUs), personality identity units (PINs) and semantic information units. Physiological covert recognition is measured by SCR and is the second route that mediates reactions to familiar faces. This theory can be explained by the disconnection of FRUs or that it may be that the face recognition system is intact but has been disconnected from a higher system enabling their conscious awareness. [3]

The parallel distributing process is a theory that proposes it would be easier to relearn previous known faces rather than to learn new ones. This process has three steps: the distributed information is represented, memory and knowledge for some things are not stored explicitly but are connected between nodes, learning can occur with gradual changes to the connections. Damaged networks are less effective by zeroing the weight of the connection. Each connection is embedded and is still faintly there, making it easier to relearn. [5]

Other theories include one proposed by Bauer, states that neurological routes mediate overt recognition. His theory went with Bruce and Young's theory that when using these three sequential stages in order, each stage will affect the next with overt mediation. The three stages are familiarity, occupation and name retrieval. [6]

Experiments

One of the first studies into the diversion of pathways of overt and covert facial processing was done by Bauer in 1984. [6] This study has been the basis for most of the other studies and literature that has been conducted on the topic of prosopagnosia and covert processing. Three other larger studies were performed. Event-related potential studies were done with 20 subjects who were clear of psychological disorders. This was a face study using 315 faces and a string of characters. In each trial 30 of the faces were familiar and 90 novel faces were shown. Then, the 315 faces were shown and subjects were asked which were familiar. The faces were shown again from the first trial but without a string of letters. This resulted in higher load results for overt recognition with longer reaction time. High load tasks led to the ability to recall far fewer faces when the task was performed. [7]

The second study was directly into covert facial recognition in prosopagnosia. In this study faces were taken from a set of 166 faces, hair and background were removed. In the first task, 36 pictures were shown, half actors and have politicians. When the face was shown the subject was asked if it was a politician or actor. Both the control and prosopagnosia patients were able to identify which faces were which therefore reaction time was compared. The second task was to say which of the faces were famous in a set of forty famous and forty non-famous. Prosopagnosia subjects had little ability to make this distinction. Further, the third task also showed forty famous faces but instead of a random string written names were used. The faces remained until one was decided upon to match the name. The covert recognition was only present in two tasks. This was not on the first task which was meant to prime and lead to the fact that the prime may be the impairment of prosopagnosia. [2] SCR tests are often used to test covert facial processing but none of the experiments displayed significant results [8]

Facial recognition in disorders

There are several problems that may damage the ability to properly perceive faces, many of these don't have effects on both the covert and overt recognition of faces. Many of these problems only have an effect on the overt recognition of faces and leave the covert recognition intact.

Prosopagnosia is a disorder which causes the inability to use overt facial recognition. [9] While people suffering from prosopagnosia often cannot identify whose face they are looking at they usually show signs of covert recognition. This can be seen in their ability to accurately guess information during forced choice tasks. [2] Patients who are unable to identify faces of people that they know are still able to accurately guess information on the owners of the faces such as their professions and names. [10] When asked how confident of their answers the patients were, they would often give low ratings of confidence despite their high accuracy during the tests. [2] This shows that they are unable to overtly recognize the face but they are still able to recall information on the owners despite the fact that they can't identify the owner. [11]

While prosopagnosia patients are unable to overtly recognize faces, patients with Capgras delusion are unable to covertly recognize faces. People suffering from Capgras delusion are able to properly identify a face, but lack the covert recognition that is normally evoked by a familiar face. Before the delusion set in patients would normally have a sensation of familiarity and have a heightened response to faces that they recognize. Once the delusion has set in the patients no longer feel that the face they are looking at is familiar to them and they can't access the feelings they normally held for the owner of the face despite the fact that they can properly identify who the face belongs to. This condition causes patients with Capgras delusion to believe that the person has been replaced with a look-alike imposter. [11]

See also

Related Research Articles

Agnosia Medical condition

Agnosia is the inability to process sensory information. Often there is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss. It is usually associated with brain injury or neurological illness, particularly after damage to the occipitotemporal border, which is part of the ventral stream. Agnosia only affects a single modality, such as vision or hearing. More recently, a top-down interruption is considered to cause the disturbance of handling perceptual information.

Capgras delusion is a psychiatric disorder in which a person holds a delusion that a friend, spouse, parent, or other close family member has been replaced by an identical impostor. It is named after Joseph Capgras (1873–1950), a French psychiatrist.

The Fregoli delusion is a rare disorder in which a person holds a delusional belief that different people are in fact a single person who changes appearance or is in disguise. The syndrome may be related to a brain lesion and is often of a paranoid nature, with the delusional person believing themselves persecuted by the person they believe is in disguise.

Face perception Cognitive process of visually interpreting the human face

Facial perception is an individual's understanding and interpretation of the face. Here, perception implies the presence of consciousness and hence excludes automated facial recognition systems. Although facial recognition is found in other species, this article focuses on facial perception in humans.

Prosopagnosia Cognitive disorder of face perception

Prosopagnosia, also called face blindness, is a cognitive disorder of face perception in which the ability to recognize familiar faces, including one's own face (self-recognition), is impaired, while other aspects of visual processing and intellectual functioning remain intact. The term originally referred to a condition following acute brain damage, but a congenital or developmental form of the disorder also exists, with a prevalence of 2.5%. The brain area usually associated with prosopagnosia is the fusiform gyrus, which activates specifically in response to faces. The functionality of the fusiform gyrus allows most people to recognize faces in more detail than they do similarly complex inanimate objects. For those with prosopagnosia, the method for recognizing faces depends on the less sensitive object-recognition system. The right hemisphere fusiform gyrus is more often involved in familiar face recognition than the left. It remains unclear whether the fusiform gyrus is specific for the recognition of human faces or if it is also involved in highly trained visual stimuli.

The syndrome of subjective doubles is a rare delusional misidentification syndrome in which a person experiences the delusion that they have a double or Doppelgänger with the same appearance, but usually with different character traits, that is leading a life of its own. The syndrome is also called the syndrome of doubles of the self, delusion of subjective doubles, or simply subjective doubles. Sometimes, the patient is under the impression that there is more than one double. A double may be projected onto any person, from a stranger to a family member.

Associative visual agnosia Medical condition

Associative visual agnosia is a form of visual agnosia. It is an impairment in recognition or assigning meaning to a stimulus that is accurately perceived and not associated with a generalized deficit in intelligence, memory, language or attention. The disorder appears to be very uncommon in a "pure" or uncomplicated form and is usually accompanied by other complex neuropsychological problems due to the nature of the etiology. Afflicted individuals can accurately distinguish the object, as demonstrated by the ability to draw a picture of it or categorize accurately, yet they are unable to identify the object, its features or its functions.

Visual agnosia is an impairment in recognition of visually presented objects. It is not due to a deficit in vision, language, memory, or intellect. While cortical blindness results from lesions to primary visual cortex, visual agnosia is often due to damage to more anterior cortex such as the posterior occipital and/or temporal lobe(s) in the brain.[2] There are two types of visual agnosia: apperceptive agnosia and associative agnosia.

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Inferior temporal gyrus One of three gyri of the temporal lobe of the brain

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Attentional shift occurs when directing attention to a point increases the efficiency of processing of that point and includes inhibition to decrease attentional resources to unwanted or irrelevant inputs. Shifting of attention is needed to allocate attentional resources to more efficiently process information from a stimulus. Research has shown that when an object or area is attended, processing operates more efficiently. Task switching costs occur when performance on a task suffers due to the increased effort added in shifting attention. There are competing theories that attempt to explain why and how attention is shifted as well as how attention is moved through space.

Fusiform face area

The fusiform face area is a part of the human visual system that is specialized for facial recognition. It is located in the inferior temporal cortex (IT), in the fusiform gyrus.

Prosopamnesia is a selective neurological impairment in the ability to learn new faces. There is a special neural circuit for the processing of faces as opposed to other non-face objects. Prosopamnesia is a deficit in the part of this circuit responsible for encoding perceptions as memories.

Superior temporal sulcus Part of the brains temporal lobe

The superior temporal sulcus (STS) is the sulcus separating the superior temporal gyrus from the middle temporal gyrus in the temporal lobe of the brain. A sulcus is a deep groove that curves into the largest part of the brain, the cerebrum, and a gyrus is a ridge that curves outward of the cerebrum.

Visual object recognition refers to the ability to identify the objects in view based on visual input. One important signature of visual object recognition is "object invariance", or the ability to identify objects across changes in the detailed context in which objects are viewed, including changes in illumination, object pose, and background context.

Phonagnosia is a type of agnosia, or loss of knowledge, that involves a disturbance in the recognition of familiar voices and the impairment of voice discrimination abilities in which the affected individual does not suffer from comprehension deficits. Phonagnosia is an auditory agnosia, an acquired auditory processing disorder resulting from brain damage, other auditory agnosias include cortical deafness and auditory verbal agnosia also known as pure word deafness.

Memory supports and enables social interactions in a variety of ways. In order to engage in successful social interaction, people must be able to remember how they should interact with one another, whom they have interacted with previously, and what occurred during those interactions. There are a lot of brain processes and functions that go into the application and use of memory in social interactions, as well as psychological reasoning for its importance.

In psychology, the face superiority effect refers to the phenomena of how all individuals perceive and encode other human faces in memory. Rather than perceiving and encoding single features of a face, we perceive and encode a human face as one holistic unified element. This phenomenon aids our visual system in the recognition of thousands of faces, a task that would be difficult if it were necessary to recognize sets of individual features and characteristics. However, this effect is limited to perceiving upright faces and does not occur when a face is at an unusual angle, such as when faces are upside-down or contorted in phenomena like the Thatcher effect and Pareidolia.

The face inversion effect is a phenomenon where identifying inverted (upside-down) faces compared to upright faces is much more difficult than doing the same for non-facial objects.

The occipital face area (OFA) is a region of the human cerebral cortex which is specialised for face perception. The OFA is located on the lateral surface of the occipital lobe adjacent to the inferior occipital gyrus. The OFA comprises a network of brain regions including the fusiform face area (FFA) and posterior superior temporal sulcus (STS) which support facial processing.

References

  1. ↑ Simon, Stéphane R., Asaid Khateb, Alexandra Darque, François Lazeyras, Eugene Mayer, and Alan J. Pegna (2011). "When the Brain Remembers, but the Patient Doesn't: Converging FMRI and EEG Evidence for Covert Recognition in a Case of Prosopagnosia". Cortex. 47 (7): 825–838. doi:10.1016/j.cortex.2010.07.009. PMID   20850714. S2CID   1228865.CS1 maint: multiple names: authors list (link)
  2. 1 2 3 4 5 Rivolta, Davide, Romina Palermo, Laura Schmalzl, and Max Coltheart (2012). "Covert Face Recognition in Congenital Prosopagnosia: A Group Study". Cortex. 48 (3): 344–352. doi:10.1016/j.cortex.2011.01.005. PMID   21329915. S2CID   20862714.CS1 maint: multiple names: authors list (link)
  3. 1 2 3 Bate, S.; Cook, S.J. (2012). "Covert recognition relies on affective valence in developmental prosopagnosia: Evidence from skin conductance response". Neuropsychology. 26 (6): 670–674. doi:10.1037/a0029443. PMID   22823135.
  4. ↑ Farah, Martha J.; Randall C. O'reilly & Shaun P. Vecera. (1993). "Dissociated Overt and Covert Recognition as an Emergent Property of a Lesioned Neural Network" (PDF). Psychological Review. 100 (4): 571–588. doi:10.1037/0033-295x.100.4.571. PMID   8255950.
  5. ↑ Eimer, M.; A. Gosling & B. Duchaine (2012). "Electrophysiological Markers of Covert Face Recognition in Developmental Prosopagnosia". Brain. 135 (2): 542–554. doi: 10.1093/brain/awr347 . PMID   22271660.
  6. 1 2 Young, A. W. (1992). "Face recognition impairments". Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences. 335 (1273): 47–54. doi:10.1098/rstb.1992.0006. PMID   1348137.
  7. ↑ Rodriguez, Y.S.; Fuster, J.I. & Leon, M.A.B. (2008). "Covert and Overt face processing in healthy subjects: an ERP study" (PDF). International Journal of Bioelectromagnetism. 10 (4): 246–260. Archived from the original (PDF) on 2016-06-17. Retrieved 2015-03-23.
  8. ↑ Valdés-Sosa, M.; Bobes, M. A.; Quiñones, I.; Garcia, L.; Valdes-Hernandez, P.; Iturria, Y.; Asencio, J. (2011). "Covert face recognition without the fusiform-temporal pathways". NeuroImage. 57 (3): 1162–1176. doi:10.1016/j.neuroimage.2011.04.057. PMID   21570471. S2CID   2295770.
  9. ↑ Groome, David (2014). An Introduction to Cognitive Psychology. 27 Church Road, Hove, East Sussex BN3 2FA: Psychology Press. pp. 126–134. ISBN   9781848720923.CS1 maint: location (link)
  10. ↑ Fox, C. & G. Iaria, J. Barton (2008). "Disconnection in Prosopagnosia and Face Processing". Cortex. 44 (8): 996–1009. doi:10.1016/j.cortex.2008.04.003. PMID   18597749. S2CID   20517855.
  11. 1 2 Young, Garry (2009). "In What Sense 'familiar'? Examining Experiential Differences within Pathologies of Facial Recognition". Consciousness and Cognition. 18 (3): 628–638. doi:10.1016/j.cortex.2008.04.003. PMID   18597749. S2CID   20517855.
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