Biomedical subjects

T O Halloran

Publications and source records attributed to T O Halloran.

3 recordsLinked to original sources

PubMed1993

The frame turns also: factors in differential rotation in pictures.

When pictures of simple shapes (square, diamond) were seen frontally and obliquely, (1) the shapes with a deeper extent into pictured space underwent more rotation (Goldstein, 1979), which is an apparent turning to keep an orientation toward an observer's changing position; (2) there was little effect of whether the observer knew the picture surface's orientation in real space, except that such knowledge could prevent multistability; and (3) depicted picture frames also rotated. In other experiments, figural and frame rotations were independent of each other, and rotation was shown for real frames. The rotation of depthless depictions suggests that at least two rotational factors exist, one that involves the object's virtual depth and one that does not. The nature of this second factor is discussed. Frame rotation appeared to subtract from object rotation when the two were being compared; this could explain a paradox in picture perception: Depicted orientations often seem little changed over viewpoints, despite (apparent) rotations with respect to real-space coordinates.

Adult↗

PubMed1989

Picture perception is array-specific: viewing angle versus apparent orientation.

The amount that a pictured lattice appears to be swung from its frame changes with subjects' viewpoint, in contrast with previous experiments using insufficient range of rotation. Also, this effect is shown to be independent of the physical slant of the picture surface, though not necessarily of border-shape information. Analysis of depicted headings which rotate with viewpoint, with respect to the picture plane, although the angle between these headings in virtual space hardly changes, relates these data to specific geometric properties of the perspective array as seen from the different viewpoints. Data show differential rotation of differently oriented features within a single depicted object, in a way that is dependent on task instructions. It is proposed that in picture perception, contradictory cues are resolved by combination.

Adult↗

PubMed1978

Reaction time to accelerating lines and dots on a cathode-ray tube.

Two experiments recorded the simple RT of 13 and 10 airline pilots, respectively, to accelerating lines and dots on a cathode-ray tube. In Exp. 1, dotted lines of six lengths moved in-line or frontally, and downward or to the right. Exp. 2 compared seven different in-line-moving solid lines with dot pairs of corresponding separations, and with single dots. RT increased with the length of in-line-moving solid lines but not when dotted lines were used. RT decreased with frontal movement of dotted lines. RT to dot pairs was shorter than to solid lines or single dots. Results indicate the importance of three factors: amount of movement information, visual angle, and inhibition of the retinal area stimulated.

Humans↗