Visual evoked potentials to change in coloration of a moving bar.
In our previous study we found that it takes less time to detect coloration change in a moving object compared to coloration change in a stationary one (Kreegipuu etal., 2006). Here, we replicated the experiment, but in addition to reaction times (RTs) we measured visual evoked potentials (VEPs), to see whether this effect of motion is revealed at the cortical level of information processing. We asked our subjects to detect changes in coloration of stationary (0(°)/s) and moving bars (4.4 and 17.6(°)/s). Psychophysical results replicate the findings from the previous study showing decreased RTs to coloration changes with increase of velocity of the color changing stimulus. The effect of velocity on VEPs was opposite to the one found on RTs. Except for component N1, the amplitudes of VEPs elicited by the coloration change of faster moving objects were reduced than those elicited by the coloration change of slower moving or stationary objects. The only significant effect of velocity on latency of peaks was found for P2 in frontal region. The results are discussed in the light of change-to-change interval and the two methods reflecting different processing mechanisms.
Institute of Psychology, University of Tartu, Tartu Estonia ; Doctoral School of Behavioural, Social and Health Sciences, University of Tartu, Tartu Estonia ; Institute of Public Law, University of Tartu, Tallinn Estonia.
Carolina
C
Murd
Institute of Psychology, University of Tartu, Tartu Estonia.
Kairi
K
Kreegipuu
Institute of Psychology, University of Tartu, Tartu Estonia ; Doctoral School of Behavioural, Social and Health Sciences, University of Tartu, Tartu Estonia.
Nele
N
Kuldkepp
Institute of Psychology, University of Tartu, Tartu Estonia.
Aire
A
Raidvee
Institute of Psychology, University of Tartu, Tartu Estonia ; Doctoral School of Behavioural, Social and Health Sciences, University of Tartu, Tartu Estonia.
Maria
M
Tamm
Institute of Psychology, University of Tartu, Tartu Estonia ; Estonian Academy of Sciences Estonia.
Jüri
J
Allik
color change; motion; reaction time; velocity; visual evoked potentials