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R Verlinde

Publications and source records attributed to R Verlinde.

5 recordsLinked to original sources
PubMed1994

A transparent motion aftereffect contingent on binocular disparity.

Under transparent motion conditions overlapping surfaces are perceived simultaneously, each with its own direction. The motion aftereffect (MAE) of transparent motion, however, is undirectional and its direction is opposite to that of a sensitivity-weighted vector sum of both inducing vectors. Here we report a bidirectional and transparent MAE contingent on binocular disparity. Depth (from retinal disparity) was introduced between two patterns. A fixation dot was presented at zero disparity, that is, located between the two adaptation patterns. After adaptation to such a stimulus configuration testing was carried out with two stationary test patterns at the same depths as the preceding moving patterns. For opposite directions a clear transparent MAE was perceived. However, if the adaptation directions were orthogonal the chance of a transparent MAE being perceived decreased substantially. This was subject dependent. Some subjects perceived an orthogonal transparent MAE whereas others saw the negative vector sum-an integrated MAE. In addition the behavior of the MAE when the distance in depth between adapting and test patterns was increased was investigated: it was found that the visibility of the MAE then decreased. Visibility is defined in this paper as: (i) the percentage of the trials in which MAEs are perceived and (ii) the average MAE duration. Both measures decreased with increasing distance. The results suggest that segregation and integration may be mediated by direction-tuned channels that interact with disparity-tuned channels.

Contrast Sensitivity↗
PubMed1988

A microcomputer-based, R-wave triggered system for hemodynamic measurements in the forearm.

A microcomputer (with 8088 or 80286 processor)-based, R-wave triggered system for on-line, semi-continuous measurement of blood flow of one or two limbs, simultaneous with heart rate and eventually intra-arterial blood pressure, is described. The minimal interval between measurements is approximately 4 s, allowing the accurate measurement of maximal flow after ischemia. When compared to hand-operated plethysmography, the use of this system improves the precision of the measurements, minimizes perturbations of the limb circulation and eliminates the possible bias of analysis by hand.

Adult↗