VPL-reports, 10, 1-27
Dynamic differences in the identification of orientation, color,
and facial expressions
Hans-Christoph Nothdurft
Visual Perception Laboratory (VPL) Göttingen
The paradigm of cued visual selection (Nothdurft, 2017a, www.vpl-reports.de/6/)
was tested on different features and the dynamics in the identification of orientation targets, color
targets, and facial expressions were compared. In large arrays of up to 80 items, one item (the
target) was cued at various delays after stimulus onset; observers had to identify this item and
report its properties. Performance accuracy was measured for different presentation times, Δt,
after the cue. With all features, accuracy improved with longer presentations. The data were fitted
with cumulative Gaussian functions and the presentation time for 75% correct responses, Δt75,
was estimated for each pattern and each cue delay; the values reflect the dynamics and relative
strengths of underlying neural signals. For orientation, discrimination was strongly accelerated at
cue delays 50-100 ms after the pattern onset. With longer delays, it slowed down again. For color, the
acceleration was stronger and more prolonged. It started earlier and reached its maximum about 400 ms
after stimulus onset. With longer delays, performance deteriorated but never fell back to the level
at zero delay. With facial expressions, the required presentation times were generally increased;
faster discrimination at short delays was less pronounced and not seen in all observers. Shortest
Δt75 values were reached 50-200 ms after stimulus onset, at similar delays as for orientation.
All data were used to reconstruct the signals that provide the cued discrimination of orientation,
color, and facial expressions. The link to neurophysiological studies and the evidence for different
impacts of these features on the control of spatial attention are discussed.
Published online: 23-Jan-2020
Citation: Nothdurft, H.C. (2020). Dynamic differences in the identification of orientation, color,
and facial expressions. VPL-reports, 10, 1-27,
www.vpl-reports.de/10/
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