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Biomedical subjects

H D Ellis

Publications and source records attributed to H D Ellis.

12 recordsLinked to original sources
PubMed1992

The development of face processing skills.

An early orientation to faces is followed by a gradual development of face processing skills. During the course of maturation, children acquire the ability to learn new faces and to deal with facial transformations. Some skills are achieved more quickly than others. Moreover, encoding ability in young children is somewhat different from that shown by older children. The younger groups fail to take advantage of increased inspection time and stimulus characteristics such as facial distinctiveness. They are also more likely to be confused by alterations in background context. Although with familiar faces they reveal very similar identity priming effects to older children and adults, younger children display a relative inefficiency in categorizing faces as being that of a target unless it is noticeably dissimilar. Young children are more likely than older people to prefer positive caricatures of certain faces, which is not consistent with the view that caricature effects are simple reflections of a general expertise with faces.

Aging↗
PubMed1990

Accounting for delusional misidentifications.

Accounts of the major DMSs are given using theoretical models of the functional components underlying recognition of familiar people. Thus, Capgras' syndrome is suggested to involve impairment of processes that can support 'covert' recognition of familiar faces in prosopagnosia. It therefore forms a potential 'mirror image' of the impairments underlying prosopagnosia, and earlier attempts to link the two conditions directly are questioned. Frégoli syndrome and intermetamorphosis are explained as defects at different stages of an information-processing chain. Not only are these accounts consistent with the association of different DMSs with different brain injuries, but they also offer both suggestions for new inquiries and predictions about possible preserved and impaired abilities.

Brain Damage, Chronic↗
PubMed1989

Childhood prosopagnosia.

K.D. has been unable to recognize people's faces since sustaining cerebral injury in infancy. Investigation of this disorder carried out when K.D. was aged 8 to 11 years showed that although her basic visual abilities were impaired, they were no poorer than those of other children who recognized faces without difficulty. K.D. had learned to read, but had not regained ability to recognize people's faces; instead she relied primarily on voices as a cue to person recognition. There was no evidence of any degree of overt or covert recognition of familiar faces, and K.D. also experienced problems in visual object recognition. She could, however, classify a visual input as a face, was able to perceive and imitate facial expressions, and was able to perform face matching tasks to an extent limited by her use of a feature by feature matching strategy. It is suggested that K.D.'s impairment affected higher order perceptual abilities, and is in a number of respects comparable to the impairments found in adult prosopagnosic patients.

Agnosia↗
PubMed1988

The effect of feature displacement on the perception of well-known faces.

The effect of feature displacement within two well-known faces (Terry Wogan and Cyril Smith) was examined. Image processing equipment was used to produce stimuli in which the features of an original facial image were displaced to form a number of modified images. This technique was first reported by Haig, in a recognition study in which the effect of feature displacement within unfamiliar faces was investigated. In the present experiment a perceptual judgement task was carried out in which subjects were presented with a number of modified faces and asked to judge how dissimilar these were with respect to an original image. A multi-dimensional scaling analysis of the comparative judgements of the subjects revealed a two-dimensional solution involving displacement of the eyes and mouth. A clear division between up/down and inward/outward displacement within these features (particularly the eyes) was observed. A similar pattern of results was found for both well-known faces. This result indicates that subjects were responding to changes in the facial configuration produced by the different types of feature displacement (horizontal or vertical), as opposed to movement of the features per se. Finally, the results also indicate that the displacement of inner features (mouth, eyes, nose) was more noticeable than displacement of the outer facial features (eg hairline).

Adult↗
PubMed1979

Identification of familiar and unfamiliar faces from internal and external features: some implications for theories of face recognition.

Three experiments are reported in which recognition of faces from whole faces or internal or external features was compared. In the first experiment, where the faces were of famous people, an advantage was found for identification from internal features. In the second experiment involving unfamiliar faces, however, no difference was found in recognition rates when subjects were given the internal or the external features. In a third experiment famous faces were presented and mixed with other famous faces for a recognition test. As in experiment 1, better recognition occurred from internals as compared with external features. It is argued that the internal representation for familiar faces may be qualitatively different from that for face seen just once. In particular some advantage in feature saliency may accrue to the internal or 'expressive' features of familiar faces. The implications of these results are considered in relation to general theories of face perception and recognition.

Discrimination Learning↗
PubMed1979

Similarity effects in face recognition.

Three experiments are described which examine the effects of similarity on face recognition using a new application of hierarchical clustering analysis (HCS). Experiments I and II employed a within-groups design where subjects attempted to recognize targets among decoys from the same and different cluster to the target. Common cluster membership accounted for 72% and 84%, respectively, of all false alarms in the two experiments. Absolute error rates were affected by the number of targets actually present in the array and the style of the instructions given to subjects but were not influenced by whether successive or simultaneous test presentation was employed. Experiment III used a between-subject design where targets were embedded in arrays composed from same or different clusters. False alarm rates were significantly higher for the same cluster condition, but hit rates were unaffected by recognition context. The significance of these findings for theories of face identification is discussed.

Adolescent↗
PubMed1975

Recognition of upright and inverted faces presented in the left and right visual fields.

Pictures of upright and inverted faces were unilaterally presented in either the left or right visual field. Subsequent recognition performance was found to be superior for faces falling in the left visual field regardless of orientation. The results are discussed in relation to Yin's (1970) ideas concerning a face-specific recognition system located in the right hemisphere.

Brain Mapping↗
PubMed1975

Recognizing faces.

Following a review of the stimulus and subject factors which have been found to affect recognition faces, the question of whether this process can be considered a special one is dealt with. Evidence from studies involving the development of face recognition, the recognition of inverted faces, and the clinical condition prosopagnosia is considered, and in each case found to be inadequate for the unequivocal conclusion that the processes underlying face recognition are qualitatively different from those employed in recognizing other pictorial material.

Adolescent↗