Null measurements given by cancelling forces, voltages, or whatever, are used in physics for gaining ‘objectivity’—by avoiding ‘subjective’ perceptions; but, somewhat paradoxically, null methods can be useful for studying perception itself. Here we consider cancelling opposed movements for photometry with coloured lights, and some recent experiments, carried out with John Harris, on nulling ‘real’ against opposed ‘apparent’ motion for teasing out some neural movement channels.
Get full access to this article
View all access options for this article.
References
1.
AnstisS M, 1980“The perception of apparent movement”Philosophical Transactions of the Royal Society of London, Series B290153–160.
2.
ArdenG BWealeR A, 1954“Variations in the latent period of vision”Proceedings of the Royal Society of London, Series B142258.
3.
BraddickO J, 1974“Short-range process in apparent motion”Vision Research14519–528.
4.
CavanaghPTylerC WFavreauO E, 1984“Perceived velocity of moving chromatic gratings”Journal of the Optical Society of America A1893–899.
5.
GregoryR L, 1955“A note on summation time of the eye indicated by signal/noise discrimination”Quarterly Journal of Experimental Psychology7147–148.
6.
GregoryR L, 1965“A Heterochromatic Photometer”British Patent Specification 53663/65 17 December 1965 [Reprinted in GregoryR L, 1974 Concepts and Mechanisms of Perception (London: Duckworth) pp 475–481].
7.
GregoryR L, 1977“Vision with isoluminant colour contrast: I, A projection technique and observations”Perception6113–119.
GregoryR LHarrisJ P, 1984“Real and apparent movement nulled”Nature (London)307729–730.
10.
GregoryR LHeardP F, 1979“Border locking and the cafe wall illusion”Perception8365–380.
11.
GregoryR LHeardP F, 1983“Visual dissociations of movement, position, and stereo depth: Some phenomenal phenomena”Quarterly Journal of Experimental Psychology35A217–237.
12.
PulfrichC, 1922“Die Stereoskopie im Dienste der isochromen und heterochromen Photometrik”Naturwissenschaften10569–601.
13.
RamachandranV SGregoryR L, 1978“Does colour provide an independent input to human motion perception?”Nature (London)27555–56.
14.
ThompsonP, 1982“Perceived rate of movement depends on contrast”Vision Research22377–380.
