Biomedical subjects

A W Young

Publications and source records attributed to A W Young.

At least 19 recordsLinked to original sources

PubMed1992

Face recognition impairments.

Face recognition impairments are often found in the context of brain injury involving the right cerebral hemisphere. Recognition impairments can be dissociated from impairments affecting the processing of other types of information carried by the face, such as expression. The face recognition impairments themselves take different forms, corresponding to idealized stages or levels of recognition. These types of error can also arise as transitory phenomena in normal everyday life. From these observations, psychologists have proposed functional models that characterize the organization of the face processing system in schematic form. Such models provide useful ways of summarizing what is known. More importantly, they also allow new findings to act as tests of each model's usefulness by the extent to which they can be readily accommodated or force revision. Examples of this are briefly considered, including delusional misidentification, impaired learning of new faces, disordered attention to faces, 'covert' recognition in prosopagnosia, and unawareness of impaired face recognition.

Brain Injuries↗

PubMed1992

Priming of face matching in amnesia.

Priming was studied in a task that required a speeded response to photographs of faces. On each trial, subjects viewed two faces and decided if the same person was shown twice or if two different people were shown. Both familiar and unfamiliar (i.e., well-known and unknown) faces were used, and some face pairs were repeated with a mean delay of about 10 min. Repetition was associated with faster reaction times in young subjects (Experiment 1) as well as in amnesic patients and age-matched control subjects (Experiment 2). The patients' reaction times were slower overall, although the magnitude of the priming effect did not differ from that in the control subjects. This preservation of a normal reaction-time facilitation in subjects with impaired recognition memory for faces occurred for both familiar and unfamiliar faces, suggesting that amnesia does not necessarily interfere with the acquisition of new information as indexed by this priming effect.

Adult↗

PubMed1992

Cotard delusion after brain injury.

A right-handed young man with contusions affecting temporo-parietal areas of the right cerebral hemisphere and some bilateral frontal lobe damage became convinced that he was dead (the Cotard delusion), and experienced difficulties in recognizing familiar faces, buildings and places, as well as feelings of derealization. Neuropsychological investigation while these symptoms were resolving revealed impairment on face processing tests. We suggest that these impairments contributed to his Cotard delusion by heightening feelings of unreality, and that the underlying pathophysiology and neuropsychology of the Cotard delusion may be related to other problems involving delusional misidentification.

Brain Injuries↗

PubMed1992

Neuropsychological impairment of face recognition units.

Despite the absence of "conscious", overt identification, some patients with face recognition impairments continue covertly to process information regarding face familiarity. The fact that by no means all patients show these covert effects has led to the suggestion that indirect recognition tasks may help in identifying different types of face recognition impairment. The present report describes a number of experiments with the patient NR, who, after a closed head injury, has been severely impaired at recognizing familiar faces. Investigations mostly failed to show overt or covert face recognition, but NR performed at an above-chance level in selecting the familiar face on a task requiring a forced-choice between a familiar and an unfamiliar face. This discrepancy between a degree of rudimentary overt recognition and absence of covert effects on most indirect tests was addressed using a cross-domain identity priming paradigm. This examined separately the possibility of preserved recognition for faces that NR consistently chose correctly in a forced-choice familiarity decision and those on which he performed at chance level. Priming effects were apparent only for the faces that were consistently chosen as "familiar" in forced-choice. We suggest that NR's stored representations of familiar faces are degraded, so that face recognition is possible only via a limited set of relatively preserved representations able to support a rudimentary form of overt recognition and to facilitate performance in matching and priming tasks.

Adult↗

PubMed1992

Repetition priming follows spontaneous but not prompted recognition of familiar faces.

Reaction times to make a familiarity decision to the faces of famous people were measured after recognition of the faces in a pre-training phase had occurred spontaneously or following prompting with a name or other cue. At test, reaction times to familiar faces that had been recognized spontaneously in the pre-training phase were significantly facilitated relative to an unprimed comparison condition. Reaction times to familiar faces recognized only after prompting in the pre-training phase were not significantly facilitated. This was demonstrated both when a name prompt was used (Experiments 1 and 3) and when subjects were cued with brief semantic information (Experiment 2). Repetition priming was not found to depend on prior spontaneous recognition per se. In Experiment 3, spontaneously recognizing a familiar face did not prime subsequent familiarity judgements when the same face had only been identified following prompting on a prior encounter. In Experiment 4, recognition memory for faces recognized after cueing was found to be over 90% accurate. This indicates that prompted recognition does not yield repetition priming, even though subjects can remember the faces. A fusion of "face recognition unit" and "episodic record" accounts of the repetition priming effect may be more useful than either theory alone in explaining these results.

Cues↗

PubMed1992

Neglect and visual recognition.

B.Q., a right-handed woman who had suffered a stroke affecting the right parietal region, showed visuospatial neglect and problems in recognizing seen objects and faces. Investigation of her visual recognition problems revealed a striking inability to identify the left sides of chimaeric objects and faces. Often, B.Q. would deny that the stimulus was chimaeric at all, and she was remarkably poor (though above chance) at discriminating chimaeric from normal faces. Even when left-sided details had been accurately traced or described, they were often either ignored in reporting the identities of the constituent parts of a chimaeric or assimilated in some way to the information from the right side. Neglect of the left side was more pronounced for chimaerics which approximated an individual face or object. It occurred regardless of the chimaeric's position in B.Q.'s field of vision, and was found with brief (200 ms) presentations of stimuli confined to her (perimetrically intact) right visual field. When chimaeric faces were inverted, B.Q. continued to neglect the side of the chimaeric falling to her left, which implies that the neglect did not operate in entirely object-centered coordinates. However, left-sided information could be used if it was critical in determining the identity of an object or a face. We suggest that this could explain B.Q.'s lack of neglect of individual words, for which left-sided (initial) letters are often crucial to successful recognition. An account of her deficit is proposed, involving an interaction between moderately defective pick-up of left-sided information in an object-based coding system and preserved access to stored representations of familiar visual stimuli.

Attention↗

PubMed1992

Face processing in psychiatric conditions.

Functional models of face processing have indicated that dissociations exist between the various processes involved, e.g. between familiar face recognition and matching of unfamiliar faces, and between familiar face recognition and facial expression analysis. These models have been successfully applied to the understanding of the different types of impairment that can exist in neuropsychological patients. In the present study, aspects of face processing in psychiatric patients were investigated in relation to Bruce & Young's (1986) model. Based on this functional model different predictions can be made. We contrast here the impaired expression analysis hypothesis, which is that psychiatric patients would show a deficit in facial expression recognition, but not in facial identity recognition or unfamiliar face matching, with the generalized deficit hypothesis, that patients would be impaired on all tasks. These hypotheses were examined using three forced-choice tasks (facial recognition, facial expression recognition, and unfamiliar face matching) which were presented to schizophrenic and depressed patients, and to non-patient controls. Results showed that schizophrenic patients performed at a significantly lower level than non-patient controls on all three tasks, supporting the generalized deficit hypothesis.

Adult↗

PubMed1991

Understanding covert recognition.

An implementation of Bruce and Young's (1986) functional model of face recognition is used to examine patterns of covert face recognition previously reported in a prosopagnosic patient, PH. Although PH is unable to recognize overly the faces of people known to him, he shows normal patterns of face processing when tested indirectly. A simple manipulation of one set of connections in the implemented model induces behaviour consistent with patterns of results from PH obtained in semantic priming and interference tasks. We compare this account with previous explanations of covert recognition and demonstrate that the implemented model provides the most natural and parsimonious account available. Two further patients are discussed who show deficits in person perception. The first (MS) is prosopagnosic but shows no covert recognition. The second (ME) is not prosopagnosic, but cannot access semantic information relating to familiar people. The model provides an account of recognition impairments which is sufficiently general also to be useful in describing these patients.

Adult↗

PubMed1991

Disentangling neglect and hemianopia.

In this paper we report findings which question the diagnosis of a hemianopia in B.Q., a 66-year-old lady who shows unilateral spatial neglect following a lesion to the right parietal lobe. The presence of a hemianopia has been indicated following two independent assessments of B.Q.'s visual fields. We examined B.Q.'s performance on a visuo-spatial task in which single or double stimuli were displayed left and right of a central fixation point. B.Q. failed to report left stimuli when the fixation point was continuously displayed (OVERLAP CONDITION). This performance is consistent with the suggestion of a left hemianopia as indicated by perimetric field testing. In a further condition the fixation point was extinguished prior to stimuli onset (GAP CONDITION). B.Q. consistently responded to left stimuli in the gap condition and also showed improved performance to right stimuli. Eye movements were recorded on a separate testing session, in which B.Q. showed a normal saccadic response to left targets in the gap condition, but not during the overlap condition. These results suggest that B.Q.'s failure to report left stimuli during field plotting is due to her neglecting left stimuli and not because she has a visual field defect. By using a testing procedure which reduces the severity of neglect B.Q. is able to respond to left stimuli. Reducing the severity of B.Q.'s neglect also abolishes the apparent hemianopia. Standard field plotting techniques which use a consistently displayed fixation point may not be appropriate for the testing of neglect patients' visual fields.

Aged↗

PubMed1991

Dissociable face processing impairments after brain injury.

Matched populations of head-injured patients and normal control subjects completed three "forced-choice" face processing tasks designed to test facial expression recognition, familiar face recognition, and unfamiliar face matching. We hypothesised a significant difference in the performance of the patients and controls on the three tasks, and hoped to observe individual differences in the patients' performance across tasks. As predicted the head-injured patients made significantly more errors than the controls on the forced-choice tasks. Four cases of dissociable impairments affecting only one of the face processing tasks are reported; patient JP impaired only on facial expression recognition, patients AB and HI impaired only on familiar face recognition, and patient VS impaired only on unfamiliar face matching. These dissociable impairments provide further evidence for independent cognitive processing of specific face properties.

Adult↗

PubMed1991

Routes through the face recognition system.

Two experiments are reported which seek to examine the proposition first put forward by Hay and Young (1982), that recognition of a known person after seeing his or her face proceeds through a series of sequentially organized stages. In both experiments subjects were shown a selection of famous and unfamiliar faces and required to state whether each face was familiar. They were then asked to recall semantic information and the person's name. Of all the possible response types, only some are predicted by models derived from Hay and Young (1982), and only these responses were observed in Experiment 1. In order to give as complete an account as possible of the slips and errors made by subjects, they were interrogated some days after completing the testing phase in Experiment 2. As in the first experiment, the results supported the view that distinct but successive stages are involved in everyday face recognition. The method developed here provides an extension of the "dairy" type of study of everyday recognition errors into laboratory conditions, which confirms the findings of studies of everyday errors and provides strong support for sequential models.

Adult↗

PubMed1991

Impairment of the visuo-spatial sketch pad.

A case study is presented of a female patient, ELD, who has difficulty in the immediate recall of short sequences of visuo-spatial material following a right-hemisphere aneurysm. Despite poor performance on tasks such as the Brooks Matrix and the Corsi Blocks, ELD is good at the immediate serial recall of letters even when presentation modality is visual and shows effects of phonological similarity and articulatory suppression. This pattern of performance represents a double dissociation from that which has been observed with the short-term memory patient PV (Vallar & Baddeley, 1984), who is extremely poor at serial recall of verbal material but shows no visual memory impairment. It is argued that ELD has an impairment to the visuo-spatial component of working memory (Baddeley, 1986) in the absence of any phonological loop deficit. Further investigation reveals that ELD performs poorly on mental rotation tasks and finds it difficult to use imagery mnemonics, but has no difficulty in retrieving visuo-spatial information from long-term memory so long as it was learnt before her illness.

Attention↗

PubMed1991

Covert and overt recognition in prosopagnosia.

Prosopagnosic patients suffer an inability to recognize familiar people by visual inspection of their faces. Despite the absence of overt recognition, though, some prosopagnosic patients continue to process the identities of familiar faces covertly. A longstanding controversy concerns whether the recognition deficit in prosopagnosia is specific for faces, or also affects other types of visual stimuli. We investigated whether the patient P.H., who has severe problems with within-class recognition of many types of visual stimuli, would show covert recognition for all stimuli which he cannot recognize overtly. Such a finding would be consistent with the idea that face recognition and recognition of other visually similar stimuli are performed by the same underlying functional mechanisms. We assessed this possibility with a forced-choice decision between correct and incorrect alternative names for familiar faces, cars and flowers, and with comparisons of P.H.'s ability to learn true versus untrue names to familiar faces, cars and flowers. Results indicated that P.H. does show covert recognition of cars and flowers, as well as faces. In addition, the covert effects observed in the forced-choice name decision and learning tasks used here were shown to have a potential common basis. Finally, the possibility of using covert knowledge as a basis for rehabilitation was explored. As was observed by Sergent and Poncet (1990) in their patient, P.H. could achieve some overt face recognition under very specific circumstances.

Adult↗

PubMed1991

Net energy of ensiled wet corn gluten feed in corn silage diets for finishing steers.

Two trials were conducted to determine the NE value of ensiled wet corn gluten feed (WCGF) in corn silage finishing diets for beef cattle. In Trial 1, 96 Angus-crossbred yearling steers were fed corn silage-based diets containing 0, 20, 40, or 60% ensiled WCGF. Increased dietary WCGF resulted in improved DMI (linear, P less than .05), ADG (linear; P less than .05), and feed/gain (linear, P less than .05). Levels of WCGF had no (P greater than .05) effect on fat thickness, marbling, quality grade, carcass protein, and carcass fat. In Trial 2, four Angus-crossbred yearling steers were used in a 4 x 4 Latin square design to determine the effect of feeding 0, 20, 40, or 60% WCGF on DE and ME values. Level of WCGF had no (P greater than .05) effect on dietary DE and ME values. Regression equations were developed for predicting NEm (Y = 1.51 + .0009X; R2 = .22) and NEg (Y = 1.04 + .0028X; R2 = .35) in which Y = predicted diet NE values in megacalories/kilogram and X = percentage of dietary WCGF. The NEg value increased .06 Mcal/kg for each 20% increase in WCGF. Predicted NEm and NEg values for WCGF are 1.60 and 1.32 Mcal/kg, respectively.

Adipose Tissue↗

PubMed1990

Facial neglect.

Following a stroke, a retired industrial chemist, K.L., complained that faces looked "different" and had become difficult to recognize. Investigation of this problem revealed that it particularly affected the left half of a face as seen by K.L. Defective recognition of this (left) half was found for normal faces, chimaeric faces, and for half-faces presented in isolation, whether upright or inverted. The problem was apparent for both internal and external facial features. Further studies with chimaeric faces demonstrated inattention to left-side features in K.L.'s judgements of facial expression and of resemblance between faces. Moreover, the left-half of a chimaeric face was affected even when it was itself forming part of the face positioned on the right in a display of two horizontally aligned chimaerics. K.L.'s spatial contrast sensitivity function was within normal limits for his age. He did not experience differential difficulty in recognizing the left side of everyday objects or of car-fronts (another stimulus class demanding within-category discrimination between visually similar items that display approximate left-right symmetry). He was also able to sort left or right half-stimuli correctly into the categories "human face", "dog face", or "tree". Although K.L. had a left visual field defect, the problem with faces occurred within otherwise intact parts of his field of vision. We suggest that his disorder can be considered a domain-specific form of unilateral neglect.

Aged↗

PubMed1990

Unawareness of impaired face recognition.

We report investigations of the face processing abilities of SP, a right-handed woman who had suffered a subarachnoid haemorrhage from a right middle cerebral artery aneurysm. Although she could correctly assign visual stimuli to the 'face' category without difficulty, SP performed poorly on all other face processing, tasks, including 'closure' (Mooney faces), perception of facial expression, unfamiliar face matching, and identification of familiar faces. Identification of familiar people from nonfacial cues (names) remained relatively well-preserved, but severe impairments were evident on all face recognition tasks. Her errors mostly involved either failures to find a face familiar at all, or misidentification as another familiar person. In face-name learning tasks, there was evidence of 'covert' recognition of faces she failed to recognize overtly. SP's face processing impairment remained stable across a 20-month period of investigation, yet throughout this period she did not think that she had any problems in face recognition, and continued to show lack of insight into this impairment even when directly confronted with its consequences on formal testing. In contrast, SP showed adequate insight into other physical and cognitive impairments produced by her illness, including poor memory, hemiplegia, and hemianopia. We propose that her lack of insight into her face recognition problems involves a deficit-specific anosognosia, resulting from impairment of domain-specific monitoring abilities.

Agnosia↗

PubMed1990

Repetition priming and face processing: priming occurs within the system that responds to the identity of a face.

A familiar stimulus that has recently been recognized will be recognized a second time more quickly and more accurately than if it had not been primed by the earlier encounter. This is the phenomenon of "repetition priming". Four experiments on repetition priming of face recognition suggest that repetition priming is a consequence of changes within the system that responds to the familiarity of a stimulus. In Experiment 1, classifying familiar faces by occupation facilitated subsequent responses to the same faces in a familiarity decision task (Is this face familiar or unfamiliar?) but not in an expression decision task (Is this face smiling or unsmiling?) or a sex decision task (Is this face male or female?). In Experiment 2, familiar faces showed repetition priming in a familiarity decision task, regardless of whether a familiarity judgment or an expression judgment had been required when the faces were first encountered. Expression decisions to familiar faces again failed to show repetition priming. In Experiment 3, familiar faces showed repetition priming in a familiarity decision task, regardless of whether a familiarity judgment or a sex judgment had been asked for when the faces were first encountered. Sex decisions to familiar faces again failed to show repetition priming. In Experiment 4, familiarity decisions continued to show repetition priming when a brief presentation time with encouragement to respond while the face was displayed reduced response latencies to speeds comparable to those for sex and expression judgments in Experiments 1 to 3. The results are problematic for theories that propose that repetition priming is mediated by episodic records of previous acts of stimulus encoding.

Adult↗

PubMed1990

Impaired memory for new visual forms.

A case study is presented of a female patient who has had impairment of visual recent memory following damage to the right cerebral hemisphere from rupture of a middle cerebral artery aneurysm. Her ability to remember unfamiliar faces is severely impaired in comparison with controls, as is her ability to identify the faces of celebrities who have become famous since the time of her illness in 1985. By contrast, she performs well on tests of recognition memory for words and has no problem in identifying celebrities from their names. She is also good at identifying faces of people who became famous before her illness. On tests of episodic memory, she continues to perform well at remembering familiar faces and objects, regardless of whether the test demands memory for which face/object was presented or memory for which view of a face/object was presented. Her poor memory for visual material is confined to unfamiliar faces and objects. Consequently, it is evident that she can learn new visual information so long as it relates to a familiar visual form; it is the learning of new visual forms that is impaired. A final experiment revealed that she is also poor at remembering unfamiliar voices. This raises the possibility that the basic deficit affects recent nonverbal memory and is not confined to the visual modality. Overall, the findings have important implications for the nature of recent visual memory loss, and for the way in which visual information is stored in memory.

Female↗