Academic Reading — Test 45

Reading passage

Most of us take for granted the ease with which we identify a familiar person the moment they come into view. A single glance is usually enough to tell us whether we are looking at a relative, a colleague or a complete stranger. For a small but significant proportion of the population, however, this apparently effortless skill is absent. People with prosopagnosia, a condition whose name derives from Greek words meaning "face" and "without knowledge", are unable to recognise faces, sometimes including those of their closest family members and, in extreme cases, their own reflection. The disorder offers researchers a remarkable window into how the human brain processes one of the most socially important categories of visual information. Prosopagnosia comes in two broad forms. The first, known as acquired prosopagnosia, results from damage to specific regions of the brain following a stroke, a head injury or certain degenerative illnesses. Cases of this kind were the first to be documented in the medical literature, and for many decades they were assumed to be exceedingly rare. The second form, developmental or congenital prosopagnosia, is present from early life and occurs in the absence of any obvious brain injury. People with the developmental variety often have no idea that their experience of faces differs from that of those around them, since they have never known anything else. Recent surveys suggest that the developmental form is far more common than was once believed, affecting roughly one person in fifty, which makes it one of the more widespread cognitive conditions, even if it remains poorly known among the general public. A crucial point, frequently misunderstood, is that the difficulty is specific to faces rather than a general failure of vision or memory. Individuals with the condition typically have normal eyesight and can describe the individual components of a face, such as the eyes, nose and mouth, without difficulty. What eludes them is the capacity to combine these features into a single, recognisable whole. This observation has led psychologists to propose that the brain ordinarily processes faces in a special way, treating them as integrated patterns rather than as collections of separate parts. This so-called holistic processing is thought to be precisely what fails in prosopagnosia. To compensate, affected individuals rely on alternative cues, picking out a person by their hairstyle, voice, gait, distinctive spectacles or characteristic clothing. These strategies are effective up to a point, but they collapse when, for example, a colleague changes their hairstyle or appears unexpectedly in an unfamiliar setting. Neuroscientists have identified a particular area on the underside of the brain, within a region called the fusiform gyrus, that appears to be central to recognising faces. This area, often referred to as the fusiform face area, becomes markedly more active when a person looks at a face than when they view other objects such as buildings or tools. In acquired prosopagnosia, damage to this region or to the pathways connecting it to other parts of the brain can abolish the ability to recognise faces while leaving other visual abilities intact. In the developmental form, brain scans do not usually reveal obvious structural damage; instead, researchers suspect subtle differences in how the relevant regions are wired together and communicate. There is also growing evidence that the developmental form tends to run in families, which points to a genetic contribution, although the precise genes involved have not yet been identified. The practical consequences of the condition are easy to underestimate. Failing to acknowledge an acquaintance in the street may be misinterpreted as rudeness or arrogance, and the resulting social awkwardness can lead some sufferers to withdraw from social situations altogether. Children with undiagnosed prosopagnosia may struggle to follow films in which they cannot keep track of who is who, or may appear anxious in crowded environments. For these reasons, simply receiving a diagnosis and an explanation can bring considerable relief, even though there is at present no cure. Training programmes that encourage people to attend more deliberately to particular facial features have produced modest improvements in some studies, but the gains are often small and do not always transfer to everyday life. Beyond its immediate effects on those who live with it, prosopagnosia has proved scientifically valuable because it illuminates the broader architecture of the mind. The fact that face recognition can be selectively damaged, while the recognition of words, places and objects remains intact, supports the influential idea that the brain is composed of specialised systems, each dedicated to a particular type of task, rather than a single general-purpose processor. In this sense, studying people who cannot recognise faces has taught researchers a great deal about how the rest of us do so with such apparent ease.