4. Effect of Spatial Characteristics on Temporal Discriminations Figure 9 plots the temporal JND's as a function of spatial exponent. For all four observers, thresholds increased asthe spatial exponent increased. In other words, discrimi-nating the temporal nature of the stimuli became more difﬁcult as the texture became coarser. This makes in-tuitive sense, as it would be easier to see a 1-mm object Fig. 8. Temporal JND's collapsed across spatial exponents. Here the temporal discriminations are plotted as a function of temporal exponent. Each subﬁgure is for an observer named by his initials. Fig. 9. Temporal JND's collapsed across temporal exponents. Here the temporal discriminations are plotted as a function of spatialexponent. Each subﬁgure is for an observer named by his initials. Billock et al. Vol. 18, No. 10/October 2001/J. Opt. Soc. Am. A 2411