ABSTRACT
This chapter shows that stimulus size and stimulus duration have a very similar effect on the contrast threshold. In the temporal case, using the traditional adjustment method, the average luminance level of the stimulus was held constant during the entire measuring period. A purely spatial stimulus is, by definition, a static pattern without any changes in time, neither movement nor flicker. A homogeneously illuminated target field is used for the temporal stimulus and the luminance level is varied sinusoidally in time. The temporal stimulus was a flickering light with a dark period before and after the stimulus period. The temporal parameter is the presentation time of the sinusoidally flickering light and is the analogue in the temporal domain of the grating width in the spatial domain. For a spatial stimulus the luminance is sinusoidally modulated in space and appears as a blurred line pattern which will be referred to as a sinusoidal grating or just a grating.
