Biomedical subjects

H Leder

Publications and source records attributed to H Leder.

14 recordsLinked to original sources

PubMed2002

[Solid-pseudopapillary tumors in childhood].

We report on fife female patients with solid pseudopapillary tumors of the pancreas. The tumors are extremely rare in children. They occur mainly in adolescent and young adult females. The tumors are neoplasms of low malignancy with infrequent metastases, for instance, in the liver or the peritoneum. Although the tumors had reached a large diameter, all of them underwent complete tumor resection. After that the patients have a very good prognosis. Thus, so it is important to distinguish solid-pseudopapillary tumors from other tumors of the pancreas.

Child↗

PubMed2001

Configural features in the context of upright and inverted faces.

When faces are turned upside down, recognition is known to be severely disrupted. This effect is thought to be due to disruption of configural processing. Recently, Leder and Bruce (2000, Quarterly Journal of Experimental Psychology A 53 513-536) argued that configural information in face processing consists at least partly of locally processed relations between facial elements. In three experiments we investigated whether a local relational feature (the interocular distance) is processed differently in upside-down versus upright faces. In experiment 1 participants decided in which of two sequentially presented photographic faces the interocular distance was larger. The decision was more difficult in upside-down presentation. Three different conditions were used in experiment 2 to investigate whether this deficit depends upon parts of the face beyond the eyes themselves; displays showed the eye region alone, the eyes and nose, or the eyes and nose and mouth. The availability of additional features did not interact with the inversion effect which was observed strongly even when the eyes were shown in isolation. In experiment 3 all eyes were turned upside down in the inverted face condition as in the Thatcher illusion (Thompson, 1980 Perception 9 483-484). In this case no inversion effect was found. These results are in accordance with an explanation of the face-inversion effect in which the disruption of configural facial information plays the critical role in memory for faces, and in which configural information corresponds to spatial information that is processed in a way which is sensitive to local properties of the facial features involved.

Adult↗

PubMed2000

When inverted faces are recognized: the role of configural information in face recognition.

The identification of upright faces seems to involve a special sensitivity to "configural" information, the processing of which is less effective when the face is inverted. However the precise meaning of "configural" remains unclear. Five experiments are presented, which showed that the disruption of the processing of relational, rather than holistic, information largely determines the occurrence as well as the size of the face-inversion effect. In Experiment 1, faces could be identified either by unique combinations of local information (e.g. a specific eye colour plus hair colour) or by unique relational information (e.g. nose-mouth distance). The former showed no inversion effect, whereas the latter did. A combination of local and relational information (Experiment 2) again produced an inversion effect, although this effect was smaller than that found when only relational information was used. The results were replicated in Experiment 3 when differences in the brightness of local features were used instead of specific colour combinations. Experiment 4 used different retrieval conditions to distinguish relational from holistic processing, and demonstrated again that spatial relations between single features appeared to provide crucial information for face recognition. In Experiment 5, the importance of relational information was confirmed using faces that also varied in the shapes of local features.

Adult↗

PubMed1999

Matching person identity from facial line drawings.

The processing of facial line drawings was investigated in either simultaneous or sequential matching trials with either the same or different viewpoint, showing pictures of faces either in the same modes (both photographs or line drawings) or different modes (one in each mode). Line drawings were particularly difficult to match in memory rather than under perceptual conditions, and line drawings did not allow the creation of efficient structural codes. These deficits of line representations underline the assumption that the face-processing system is inflexible when it is confronted with edge-based material.

Adult↗

PubMed1998

Your eyes only? A test of interactive influence in the processing of facial features.

The holistic hypothesis in face processing was tested in 3 experiments. Holistic processing was conceptualized as interactive influence of facial features on the perceptual representation of faces. In Experiment 1, 3 facial features (eye distance, width of nose, size of mouth) were varied on 3 values per feature. Photographs and blurred versions were used. Participants assigned each stimulus face to 1 of 2 target faces according to similarity. The data were evaluated by the logit model that provides a direct test of interactive influence of the features on participants' performance. The interactive-processing hypothesis was not confirmed. The results were replicated in Experiment 2, in which 2 features with 5 values each were used and data of individual participants were evaluated, and in Experiment 3, in which a reduced presentation time of 250 ms was used. It is concluded that facial features are processed and represented independently.

Adult↗

PubMed1998

Local and relational aspects of face distinctiveness.

Distinctiveness contributes strongly to the recognition and rejection of faces in memory tasks. In four experiments we examine the role played by local and relational information in the distinctiveness of upright and inverted faces. In all experiments subjects saw one of three versions of a face: original faces, which had been rated as average in distinctiveness in a previous study (Hancock, Burton, & Bruce, 1996), a more distinctive version in which local features had been changed (D-local), and a more distinctive version in which relational features had been changed (D-rel). An increase in distinctiveness was found for D-local and D-rel faces in Experiment 1 (complete faces) and 3 and 4 (face internals only) when the faces had to be rated in upright presentation, but the distinctiveness of the D-rel faces was reduced much more than that of the D-local versions when the ratings were given to the faces presented upside-down (Experiments 1 and 3). Recognition performance showed a similar pattern: presented upright, both D-local and D-rel revealed higher performance compared to the originals, but in upside-down presentation the D-local versions showed a much stronger distinctiveness advantage. When only internal features of faces were used (Experiments 3 and 4), the D-rel faces lost their advantage over the Original versions in inverted presentation. The results suggest that at least two dimensions of facial information contribute to a face's apparent distinctiveness, but that these sources of information are differentially affected by turning the face upside-down. These findings are in accordance with a face processing model in which face inversion effects occur because a specific type of information processing is disrupted, rather than because of a general disruption of performance.

Face↗

PubMed1996

Line drawings of faces reduce configural processing.

The highly specialised skill of face recognition found in humans is thought to be dependent on the processing of a combination of edge-based and surface-based information, and of single-feature as well as of configural information. An investigation was carried out into how the saliency of facial information differs between faces presented as line drawings and the same faces presented as photographs. In experiment 1, the participants showed a decreased sensitivity in their detection of changed configural properties if the faces were presented as line drawings. In experiment 2 an investigation was carried out into whether distinctiveness due to configural properties loses its impact on recognition when faces are transformed to line drawings. For each of twenty unfamiliar male faces, a more 'distinctive' version was created by moving the eye region down. The increase of distinctiveness was confirmed in a rating phase. In a later recognition test, with the same stimuli presented either as line drawings or as photographs, the more distinctive stimuli produced higher recognition rates when presented as photographs but the advantage disappeared when the same faces were presented as line drawings. The changes in sensitivity to configural properties thus contribute to the poor recognition of faces presented as line representations.

Adult↗

PubMed1992