CNS Poster 2020

1. Rapid Motor Responses Based On Perceived Brightness, Not Contrast
Cary Wang, Yuming Liu, and Marjan Persuh
Department of Social Sciences, Human Services and Criminal Justice, Borough of Manhattan Community College
The City University of New York
| Introduction
Recent evidence suggests that rapid motor
responses are based on local contrast and not
on perceived brightness (1). Authors used
stimuli similar to the classical Simultaneous
Contrast Illusion.
Note that in this illusion perceived brightness
and local contrast have the same direction.
We studied priming in the context of White’s
Illusion (2), in which perceived brightness and
local contrast have the opposite direction.
| Experiment 1
White’s Illusion was used to manipulate the
perceived brightness of primes, while
participants responded to targets presented at
the center of the display.
| Method
In a separate experiment we used a double
staircase procedure to estimate the brightness
of primes. These values were then used as the
target values.
Participants made speeded responses to
targets that appeared after primes at different
stimulus onset asynchronies (SOAs).
| Results
-15
-10
-5
0
5
10
15
20
25
30
35
40
14 57 100 200 500
Incongruent-CongruentRT(ms)
SOA (ms)
Priming as a Function of SOA
ANOVA revealed a main effect of congruency
(p = .001) and SOA (p < .001). Because
congruency assignment was based on
perceived brightness these results
demonstrate that priming is based on
perception, not local contrast.
1000 ms
500 ms
SOA: 14-500ms
Response
| Experiment 2
In White’s illusion, total local contrast is
determined by a weighted contribution of
positive and negative contrast. We tested
response priming with a Modified White’s
Illusion (2) in which local contrast is uniform.
| Method
Participants made speeded responses to
targets that appeared after primes at different
SOAs.
1000 ms
500 ms
SOA: 14-86 ms
Response
| Results
ANOVA revealed a main effect of congruency
(p = .002), SOA (p < .001) as well as
significant congruency x SOA interaction (p =
.025). Priming effects increased with longer
SOAs.
-10
0
10
20
30
40
50
60
14 28 42 57 71 86
Incongruent-CongruentRT(ms)
SOA (ms)
Priming as a Function of SOA
350
370
390
410
430
450
470
490
14 28 42 57 71 86
ResponseTime(ms)
SOA (ms)
Response Time as a Function of SOA
Incongruent
Congruent
| Conclusions
Experiments 1 and 2 demonstrate that rapid
response priming is driven by subjective
brightness and not by the local contrast.
Discrepancies with previous study might be
due to the methodology of estimation of
perceived brightness.
| References
1. Schmidt, T., Miksch, S., Bulganin, L., Jäger, F., Lossin, F., Jochum, J., & Kohl, P. (2010). Response
priming driven by local contrast, not subjective brightness. Attention, Perception, & Psychophysics,
72(6), 1556–1568.
2. White, Michael. (2010). The Early History of White's Illusion. Colour: Design and Creativity. 7. 1-7.
350
370
390
410
430
450
470
490
14 57 100 200 500
ResponseTime(ms)
SOA (ms)
Response Time as a Function of SOA
Incongruent
Congruent
Contact: cwang205@fordham.edu