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Michael Cook

Publications and source records attributed to Michael Cook.

5 recordsLinked to original sources
PubMed2004

Depth of monocular elements in a binocular scene: the conditions for da Vinci stereopsis.

Quantitative depth based on binocular resolution of visibility constraints is demonstrated in a novel stereogram representing an object, visible to 1 eye only, and seen through an aperture or camouflaged against a background. The monocular region in the display is attached to the binocular region, so that the stereogram represents an object which is only partially visible to the eye that sees it. The results show that this feature is necessary for quantitative depth, which is not found for a fully visible monocular object in the same location, and that depth in these displays, although very precise, is not based on fusional Stereopsis. The findings provide clear support for the existence of a process of da Vinci Stereopsis, but one more sophisticated than the one proposed by K. Nakayama and S. Shimojo (1990).

Depth Perception↗
PubMed2003

Monocular discs in the occlusion zones of binocular surfaces do not have quantitative depth--a comparison with Panum's limiting case.

Da Vinci stereopsis is defined as apparent depth seen in a monocular object laterally adjacent to a binocular surface in a position consistent with its occlusion by the other eye. It is widely regarded as a new form of quantitative stereopsis because the depth seen is quantitatively related to the lateral separation of the monocular element and the binocular surface (Nakayama and Shimojo 1990 Vision Research 30 1811-1825). This can be predicted on the basis that the more separated the monocular element is from the surface the greater its minimum depth behind the surface would have to be to account for its monocular occlusion. Supporting evidence, however, has used narrow bars as the monocular elements, raising the possibility that quantitative depth as a function of separation could be attributable to Panum's limiting case (double fusion) rather than to a new form of stereopsis. We compared the depth performance of monocular objects fusible with the edge of the surface in the contralateral eye (lines) and non-fusible objects (disks) and found that, although the fusible objects showed highly quantitative depth, the disks did not, appearing behind the surface to the same degree at all separations from it. These findings indicate that, although there is a crude sense of depth for discrete monocular objects placed in a valid position for uniocular occlusion, depth is not quantitative. They also indicate that Panum's limiting case is not, as has sometimes been claimed, itself a case of da Vinci stereopsis since fusibility is a critical factor for seeing quantitative depth in discrete monocular objects relative to a binocular surface.

Depth Perception↗
PubMed2002

Striking a chord with amnesic patients: evidence that song facilitates memory.

There have been several reports in the literature, mainly anecdotal, of amnesic patients demonstrating an ability to learn and remember song. Yet there has been little systematic investigation of this phenomenon. In this paper we report findings from three experiments investigating memory for song in two amnesic patients, Joan and Nellie. In the first study we explored recognition memory for various elements of song (i.e. lyrics, melody, lyrics and melody combined) and found that amnesic patients were better than chance at distinguishing studied from novel materials when given explicit instructions. In experiment 2, the ability to generate lyrics and melody was explored in one patient. Although this patient could only generate melodies, her performance in this modality was equivalent to that of matched controls. Memory for the semantic content of song was investigated in a final study using explicit testing conditions. The results showed that both patients were significantly better than chance at identifying correct responses, indicating that they acquired and retained knowledge of the general content of studied songs. These findings not only highlight the special nature of song in facilitating memory in amnesic patients, but given the level of accuracy in memory performance observed, suggest an alternative direction in rehabilitation.

Adult↗