Abstract
Purpose::
To compare the effect of yellow and neutral filters on the relative contributions of low and high Spatial-Frequencies (SF) in the perception of natural scenes.
Methods::
Subject’s instruction ws to name verbally the category of the scene displayed. Four scene categories were considered: indoor, landscape, city and highway. Four different test images were generated for each scene category: non-filtered, high-pass filtered, low-pass filtered and hybrid images. Hybrid images were constituted by the low SF of one scene and the high SF of another scene (Schyns, Oliva, 1994, Psychol. Sc. 195-200). Images were displayed for 30ms. Each subject achieved the experiment wearing yellow and neutral filters and for low and high contrast scenes. Eighteen adults participated in the study.
Results::
Proportions of correct responses with yellow filters were compared to those with neutral filters. Results showed that performances for low SF and high SF scenes, displayed separately, were similar for both filters (t = 1.11; p = 0.2807). When subjects wore yellow filters, their decisions were strongly biased in favour of the low SF scenes of the hybrid images (t = 4.55; p = 0.0003). Subjects exhibited the same preference when images were displayed at a lower contrast (t = 3.08; p = 0.0069). Comparing both contrast levels, results showed that subjects tended to prefer the low SF of the hybrid images when the contrast decreased (t = 9.53; p < 0.0001 and t = 8.88; p < 0.0001 respectively for yellow and neutral filters).
Conclusions::
The current study showed that when subjects wore yellow filters, they tended to recognize more frequently the low SF scenes than the high SF scenes of the hybrid images. These results are in line with those of Ray and colleagues’ study (Ann. N.Y. Acad. Sci. 2005 283-293) suggesting that yellow filters can improve magnocellular function. The magnocellular stream is indeed involved in the processing of low SF. The current results also confirmed previous works showing that the preference for low SF of hybrid images was enhanced as scene contrast decreased (Goury, Giraudet, 2005, Perception 138).
Keywords: scene perception • image processing