The Fröhlich effect: a consequence of the interaction of visual focal attention and metacontrast

Usually we assume that the central nervous system preserves temporal sequences. Here we show that moving objects--in the context of behaviour often dangerous ones--are seen with a shorter latency than stationary (flashed) objects. In addition moving objects are deblurred. Two mechanisms contribute to this functional specialisation: cue-induced visual focal attention and metacontrast. Under unnatural conditions these mechanisms lead to an optical illusion first described by Fröhlich [Fröhlich, F. W. (1923). Uber die Messung der Empfindungszeit. Zeitschrift für Sinnesphysiologie, 54, 58-78].