Evidence for the latency-time explanation of the Pulfrich phenomenon

Abstract.— The explanation of the F'ulfrich stereophe-nomenon has been based on the laws of stereoscopic depth and angular disparity, together with the assumption that the timing of the neural discharges from the retina of the Eltered eye is delayed. If this hypothesis is plausible the stereoscopic effect is at least reduced when the pendulum swings vertically in relation to the condition in which the path of the pendulum crosses the observer's line of sight horizontally, because the vertical disparity is ineffective as a depth cue. The results of the present experiment show that the Pulfrich phenomenon is reduced when the pendulum swings vertically.     

Visual stimulus intensity and location probability: Interactive effects on choice reaction time

Three prevalent models predict different stimulus intensity effects on RT. These are: the serial-stage model (additivity), the variable criterion model (larger intensity effects with slower responding), and the temporal overlap model (smaller intensity effects with slower responding). The predictions were tested in a dual-response situation including oculomotor and manual responses (RT). Other variables were stimulus location probability (expectancy), foreperiod (alertness), and stimulus intensity (encoding. In Experiment I, an Intensity x Probability interaction was found such that the intensity-effect was smaller at low stimulus probability. Three further experiments were performed in order to specify some of the conditions relevant for this phenomenon. The results are consistent with the temporal-overlap interpretation. It was suggested that the obtained interaction results from a processing delay due to increased demands for cognitive and response processing (Stanovich & Pachella, 1977), or to the attention switch to an unexpected S-R event.