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Biomedical subjects

H D Ellis

Publications and source records attributed to H D Ellis.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1985

Cold and performance: the effects of information load, analgesics, and the rate of cooling.

In the first experiment, 8 subjects took part in two experimental sessions--one after receiving one of two kinds of analgesic and the other after receiving a placebo. For each session, subjects completed 8- and 4-choice versions of a serial choice reaction time (SCRT) task at three times: before, during, and after exposure in a cold room at -5 degrees C. Body temperatures were monitored throughout and comfort ratings were recorded. The results indicated that cold increased error rate on the SCRT task, particularly for the 8-choice version which was also associated with faster RTs. However, a speed-accuracy tradeoff explanation for the data was discounted on the grounds that, although overall latencies were faster in the cold compared with precold, these were no faster than postcold RTs. The analgesics had no effect on comfort nor did they have an interpretable effect on performance. In experiment 2, where cooling was much slower for 5 subjects, no such increase in error rate on the SCRT task was observed. Similarly slow cooling did not impair general intellectual ability as measured by Raven's Progressive Matrices.

Adult↗
PubMed1984

The effects of stimulus and subject factors on a face matching task.

An initial experiment revealed that, under very rapid viewing conditions, the usual asymmetry for face recognition occurred only for low-detail facial sketches. Photographs and medium-detail sketches failed to show VF asymmetry. A further experiment revealed that the effect was unlikely to be attributable to discrimination difficulties; this experiment, however, replicated the LVF superiority on low-detail faces only for male subjects. These results are briefly examined in the light of Sergent's theoretical interpretation of hemisphere asymmetry (Sergent, J. Percept. Psychophys. 31, 451-461, 1982). They are also discussed in relation to sex differences in cerebral asymmetry.

Adult↗
PubMed1983

Mea culpa? A study of the relationships among personality traits, life-events and ascribed accident causation.

On the basis of their own reports, accident victims attending a casualty department were independently assigned either to a causal group (n = 25), i.e. apparently culpable in causing their accident, or a non-causal group (n = 25). Comparisons were made between these two groups of patients on: (1) sociodemographic characteristics; (2) locus of control; (3) recent life-events; and (4) cognitive failures. The groups differed only in their tendency to perceive locus of control as being internal (causal group) or external (non-causal group).

Accidents↗
PubMed1981

Within-race and between-race recognition of transformed and untransformed faces.

Numerous studies have shown that people from one racial group experience difficulties in remembering the faces of people from other racial groups. Two experiments are reported that explore the phenomenon more fully by examining subjects' ability to recognize faces transformed slightly in pose between study and test. Published work shows that white subjects can recognize such transformed white faces as well as they identify untransformed faces. In the first experiment, it was shown that white subjects were unable to recognize transformed black faces. The second experiment, following the pilot study, investigated recognition of both black and white, transformed and untransformed faces by Europeans and Africans. This study revealed that people from one racial group are particularly disadvantaged in recognizing other-race faces that have undergone transformation. The results are discussed in relation to learning approaches to face memory.

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↗