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Biomedical subjects

D C Hay

Publications and source records attributed to D C Hay.

At least 19 recordsLinked to original sources
PubMed2001

Interaction between hnRNPA1 and IkappaBalpha is required for maximal activation of NF-kappaB-dependent transcription.

Transcriptional activation of NF-kappaB is mediated by signal-induced phosphorylation and degradation of its inhibitor, IkappaBalpha. NF-kappaB activation induces a rapid resynthesis of IkappaBalpha which is responsible for postinduction repression of transcription. Following resynthesis, IkappaBalpha translocates to the nucleus, removes template bound NF-kappaB, and exports NF-kappaB to the cytoplasm in a transcriptionally inactive form. Here we demonstrate that IkappaBalpha interacts directly with another nucleocytoplasmic shuttling protein, hnRNPA1, both in vivo and in vitro. This interaction requires one of the N-terminal RNA binding domains of hnRNPA1 and the C-terminal region of IkappaBalpha. Cells lacking hnRNPA1 are defective in NF-kappaB-dependent transcriptional activation, but the defect in these cells is complemented by ectopic expression of hnRNPA1. hnRNPA1 expression in these cells increased the amount of IkappaBalpha degradation, compared to that of the control cells, in response to activation by Epstein-Barr virus latent membrane protein 1. Thus in addition to regulating mRNA processing and transport, hnRNPA1 also contributes to the control of NF-kappaB-dependent transcription.

Animals↗
PubMed2000

Testing instance models of face repetition priming.

Two experiments examining repetition priming in face recognition are reported. They employed eight rather than the more usual two presentation trials so that the prediction made by Logan's (1988) instance model of power function speedup of response time (RT) distributions could be examined. In Experiment 1, we presented the same photograph on each trial; in Experiment 2, we presented photographs of varying poses. Both experiments showed repetition priming effects for familiar and unfamiliar faces, power function speedup for both the mean and the standard deviation of RT and the power function speedup of the quanties of the RT distributions. We argue that our findings are consistent with the predictions made by the instance model and provide an explanatory challenge for alternative theoretical approaches.

Adult↗
PubMed1994

Movement, face processing and schizophrenia: evidence of a differential deficit in expression analysis.

Three dynamic face-processing tasks based on the Bruce & Young (1986) functional model of face processing were presented to 10 schizophrenic and 10 depressed inpatients and to 10 non-patient subjects. Familiar face recognition, facial expression recognition and unfamiliar face matching were examined. Schizophrenic patients' performance was significantly poorer than that of depressed patients and non-patient controls. Significantly lower scores were obtained on the facial expression recognition task than on the familiar face recognition task. There was a differential pattern of group performance on each of the three tasks: schizophrenic and depressed patients were as accurate as non-patient controls on the familiar face recognition task, but significantly less accurate than non-patient controls on the unfamiliar face-matching task. Schizophrenic patients were significantly less accurate than depressed patients and non-patient controls on the facial expression recognition task. The results are contrasted with an analogous static face-processing study.

Adolescent↗
PubMed1993

Impaired discrimination of familiar from unfamiliar faces.

We report investigations of the face processing abilities of J.T., a man who had suffered a right hemisphere stroke. J.T. showed a marked problem in discriminating between familiar and unfamiliar faces, with no corresponding problem in discriminating familiar from unfamiliar names. The problem with faces was still found 2 years after the stroke, but had resolved at long-term follow-up (9 years post stroke). When given unlimited time to respond, J.T. did not show any problem in recognising familiar faces, but tended to think that he recognised unfamiliar faces. When under time pressure, however, J.T. also failed to recognise a number of familiar faces which he could readily identify when the time pressure was removed. J.T.'s ability to remember a face and to think of other people who might be similar in appearance was affected by whether or not the face seemed familiar or unfamiliar to him. Hence, whatever underlay the spurious sense of familiarity was sufficient to produce real differences between the way in which genuinely unfamiliar and spuriously familiar faces were seen, leading us to suggest that his impaired discrimination of unfamiliar from familiar faces reflected a malfunction of face recognition units.

Aged↗
PubMed1993

Face perception after brain injury. Selective impairments affecting identity and expression.

Current theoretical models of face perception postulate separate routes for processing information needed in the recognition of a familiar face, for matching photographs of unfamiliar faces and for the analysis of facial expressions. The present study investigated this claim in a group of ex-servicemen who had sustained unilateral brain injuries affecting posterior areas of the left or right cerebral hemisphere. Care was taken to confirm the nature of impairment by using two different tasks to assess each of the three theoretically defined abilities (leading to a total of six tasks). We adopted a stringent application of the double dissociation methodology to investigate the pattern of performance across tasks of individual ex-servicemen. A selective impairment was defined as a significantly impoverished performance on both tests of a specific ability, while all other tasks were performed within normal limits. In addition, we used both accuracy and response latency measures to substantiate evidence for spared or defective abilities. The results showed selective impairments of all three abilities on accuracy scores. Response latency data confirmed the finding of a selective deficit in the processing of facial expressions, but produced evidence suggesting that impairments affecting familiar face recognition and unfamiliar face matching were not completely independent from each other in this group of ex-servicemen.

Brain Injuries↗
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

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↗
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↗
PubMed1987

Configurational information in face perception.

A new facial composites technique is demonstrated, in which photographs of the top and bottom halves of different familiar faces fuse to form unfamiliar faces when aligned with each other. The perception of a novel configuration in such composite stimuli is sufficiently convincing to interfere with identification of the constituent parts (experiment 1), but this effect disappears when stimuli are inverted (experiment 2). Difficulty in identifying the parts of upright composites is found even for stimuli made from parts of unfamiliar faces that have only ever been encountered as face fragments (experiment 3). An equivalent effect is found for composites made from internal and external facial features of well-known people (experiment 4). These findings demonstrate the importance of configurational information in face perception, and that configurations are only properly perceived in upright faces.

Adult↗
PubMed1986

Face-name interference.

Interference effects between the processing of simultaneously presented photographs of faces of familiar people and printed names of familiar people were investigated. Printed names interfered with identifying faces, whereas faces did not interfere with saying printed names (Experiments 1 and 3). In contrast, faces interfered more with name categorization than names interfered with face categorization (Experiments 2 and 4). Despite a priori reasons as to why faces might be thought to possess functional properties different from those of other visual objects, the observed effects are comparable to those found in object-word interference studies, with photographs of faces behaving like pictures of objects and printed people's names behaving like printed names of objects. In face naming tasks, the presence of related names produced more interference than did the presence of unrelated names (Experiment 1). This effect was examined in greater detail in Experiment 3, where we found that the effect arises when the face and the name belong to people of similar appearance. An effect of common category membership was not found in Experiment 3. Experiment 5, however, showed that names of people highly associated with the person whose face is presented also produce more interference than do names of unrelated people.

Association↗
PubMed1985

Right cerebral hemisphere superiority for constructing facial representations.

Right-handed people were asked to decide whether or not stimuli presented in the left visual hemifield (LVF) or in the right visual hemifield (RVF) were faces. Manual reaction times and error rates were recorded under three conditions. In Condition A, stimuli were line drawings of faces and moderately scrambled nonfaces made by rearranging the facial features. In Condition B, stimuli were line drawings of faces and highly scrambled nonfaces. In Condition C, stimuli were line drawings of faces and objects. The results show that faces are identified more quickly from the LVF than from the RVF in Condition A (faces vs moderately scrambled nonfaces), with no visual hemifield difference in reaction times to Condition B (faces vs highly scrambled nonfaces) and Condition C (faces vs objects). These findings are taken to indicate that both cerebral hemispheres are able to assign stimuli to the "face" category, but the right hemisphere is better than the left hemisphere at constructing facial representations. This cerebral hemisphere difference in ability to construct facial representations becomes evident when a detailed representation is required (as in Condition A).

Cerebral Cortex↗
PubMed1985

Familiarity decisions for faces presented to the left and right cerebral hemispheres.

Right-handed subjects were asked to decide whether or not faces presented briefly in the RVF or in the LVF were familiar (familiar faces were those of famous people). This task avoids the need for extensive semantic processing or temporary storage involved in conventional naming or identification tasks, and thus eliminates the contribution of such factors to any observed asymmetry. The resulting finding of faster reaction times to LVF faces, with no overall visual hemifield difference in error rates, is taken to indicate a right-hemisphere superiority either in the processes used to construct facial representations or in the accessing of face recognition units, or both.

Adult↗