The perception of motion transparency: a signal-to-noise limit.
A number of studies were conducted to determine how many transparent motion signals observers could simultaneously perceive. It was found that that the limit was two. However, observers required a signal intensity of about 42% in order to perceive a bi-directional transparent stimulus. This signal level was about three times that required to detect a uni-directional motion signal, and higher than was physically possible to achieve in a tri-directional stimulus (in a stimulus in which the different transparent signals are defined only by direction). These results indicate that signal intensity plays an important role in establishing the transparency limit and, as a consequence, implicates the global-motion area (V5/MT) in this process.
Edwards
Mark
M
School of Psychology, Australian National University, Canberra 0200, Australia. mark.edwards@anu.edu.au
Greenwood
John A
JA
D004192:Discrimination, Psychological; D005556:Form Perception; D006801:Humans; D009039:Motion Perception; D010775:Photic Stimulation / Q000379:methods; D011594:Psychometrics; D011601:Psychophysics; D012684:Sensory Thresholds