Detecting Cross-Modal Thresholds of Simultaneity

An important topic in experimental psychology concerns the detection of simultaneity. This is defined as the ability to determine that two events have taken place at the same time even if the information has arrived via more than one sensory input. Determination of human simultaneity detection has important implications in vision because simultaneity indicates that two events might have arisen from one object. This, in turn, helps to define grouping relationships in the real world. For example, a sound associated with a movement helps us localize and identify sound sources. It is also important to know when two events are not simultaneous. This determination allows us to make temporal order judgments, which can help us form predictive relationships between events. This is seen, for instance, in the learning of new words. If we were unable to predict that the syllable "for" preceded "ess," we would be unable to learn the word forestry. I have used computer programming in MATLAB to assess different qualities of cross-modal simultaneity. Research shows certain preference for sound to precede light, and can illuminate the separation needed to tell two sounds apart.