If the FSDP is related to the properties of "perceptual" mechanisms of the human visual system (rather than eye movements, etc.
If the FSDP arises because of an asymmetry in the visual mechanisms responding to motion, one would predict that the upper threshold frequency for the detection of motion (the RFTF) for downward motion (T-B scanning) would be lower than for the other three principal directions.
The observation that the RFTF is significantly lower when a screen is scanned T-B than when scanned L-R, R-L, or B-T (Figure 8) provides evidence that the FSDP arises from an asymmetry in visual motion detection mechanisms.
These experiments suggest that the FSDP is attributable to an asymmetry in the sensitivity of visual motion detection mechanisms.
EXPERIMENT 5: RELATIONSHIP BETWEEN THE FSDP AND HISTORY OF VIEWING RASTER-SCANNED DISPLAYS
If the FSDP arises because of adaptation, some correlation between TV/VDT viewing history and the asymmetry in RFTFs might be expected.
In general, these data support the hypothesis that the FSDP is related to adaptation caused by previous exposure to TVs or VDTs, though results were variable and only three participants had not viewed a raster-scanned display during the previous month.
These results strongly support the hypothesis that the FSDP arises from adaptation to TVs and VDTs.
The FSDP is a directional asymmetry in sensitivity and as such should be apparent only when the visual mechanisms that respond to motion are active.
Corbett and White (1976) suggested that the FSDP might be attributable to adaptation to TVs, VDTs, and other raster-scanned displays that are conventionally scanned T-B.