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Biomedical subjects

P J Stappers

Publications and source records attributed to P J Stappers.

7 recordsLinked to original sources

Presence for design: conveying atmosphere through video collages.

Product designers use imagery for inspiration in their creative design process. To support creativity, designers apply many tools and techniques, which often rely on their ability to be inspired by found and previously made visual material and to experience the atmosphere of the user environment. Computer tools and developments in VR offer perspectives to support this kind of imagery and presence in the design process. But currently these possibilities come at too high a technological overhead and price to be usable in the design practice. This article proposes an expressive and technically lightweight approach using the possibilities of VR and computer tools, by creating a sketchy environment using video collages. Instead of relying on highly realistic or even "hyperreal" graphics, these video collages use lessons learned from theater and cinema to get a sense of atmosphere across. Product designers can use these video collages to reexperience their observations in the environment in which a product is to be used, and to communicate this atmosphere to their colleagues and clients. For user-centered design, video collages can also provide an environmental context for concept testing with prospective user groups.

Communication↗

Cubby: a unified interaction space for precision manipulation.

Precision manipulation in surgical simulation poses special requirements on a VR system. One such requirement is unification, i.e. that the user manipulates a virtual object where it appears. We have designed Cubby, a system of which the visualization part was presented at MMVR97 [3], for precision manipulation and unification. In an experiment Cubby was compared with a single screen head-tracked display, both in a unified and a non-unified version. The results show that subjects could manipulate virtual objects in Cubby with significantly higher accuracy and preferred it to the single screen head-tracked display. Though no significant difference in accuracy between the unified and non-unified conditions could be shown, subjects did prefer the unified over the non-unified condition within both setups.

Computer Simulation↗

A system for investigating 3-D form perception.

This paper describes a noninvasive, relatively inexpensive, and simple to use system developed by the authors for monitoring the visual inspection behavior of someone free to select any viewing angle of an object by moving about it while at the same time being able to rotate it. A demonstration experiment verifies the potential of the system to study 3-D form perception.

Adult↗

An empirical evaluation of the visual rightness theory of pictorial composition.

This research tested the visual rightness theory of pictorial composition's assertion that the induced organizational structure of a visually right (i.e., "good") design is perceptually salient and judged superior by anyone viewing it regardless of his or her training in the visual arts. Stimuli for Experiments 1 and 2 consisted of 16 reproductions of paintings by renowned artists and an experimentally reconstructed less-well-organized version of each art stimulus. It was found that design professionals (Experiment 2) were significantly more successful at detecting the original versions than were participants untrained in the visual arts (Experiment 1) (hit rates = 64% and 55%, respectively). In Experiment 3 participants replaced a major structural element removed from each of six pictures of the stimulus set at the location where they thought it appears in the original. A significant number of untrained participants and those with training in design theory were in agreement as to the location of each element within its pictorial field; the location chosen conformed to its compositional structure but not its actual location in the original. Findings demonstrate that the ability to detect the induced structural skeleton of a painting resulting from a visually right design does not require expert knowledge of design principles whereas the ability to discriminate between several articulation possibilities of the same composition does require formal training.

Adult↗

Matching proprioceptive to visual speed affected by nonkinematic parameters.

In an experiment three subjects adjusted the speed of a treadmill under their feet to match the speed of a flow pattern visible in front of their feet. Although the subjects could perform the matching fairly well, their adjustment varied with the effort of walking manipulated. This finding rules out a purely kinematic-matching hypothesis.

Acceleration↗

Forms can be recognized from dynamic occlusion alone.

Direct and indirect theories of perception differ on whether form perception depends on higher order invariants or on features in the retinal image. The present paper describes a demonstration that an object can be recognized through a higher order pattern (dynamic occlusion) without any of the object's features being displayed. Stimuli consist of computer stimulations of black wireframe objects moving in front of, and occluding, a random layout of point lights on a black background. In this way, no single videoframe of the stimuli displays any of the object's features, and motion of the amodal object in front of the light points is necessary for the form to become visible. The forms can also be recognized when isoluminous colours are used for background and point lights. Finally, it is noted that, if the observer can actively control the motion of the object, e.g., by moving a computer mouse, recognition is enhanced as in Gibson's (1962) experiment on active touch.

Attention↗

Form discrimination: features or invariants?

Does form discrimination rely on feature analysis, as the indirect theory of perception supposes, or on affordances (behavioural meanings specified by invariant patterns), as direct theory states. Subjects were to indicate the position of a target in a perspective rendering of a plane, displayed for 100 msec. in a large screen projection. In one of the conditions the target disrupted the plane, in the other it did not. Although targets of the two conditions shared the same features, the disruptive targets were discriminated more often than the nondisruptive targets. This result supports the direct approach to perception which states that a perceiver discriminates behaviourally relevant patterns rather than geometrical properties.

Adolescent↗