Attention and the perception of dynamic stimuli: 
Old and new misperceptions

Elena Carbone
Visual Attention Lab
Department of Computer Science
UMass Boston

When asked to indicate the starting position of a fast moving stimulus, 
subjects make systematic errors. Instead of the actual starting 
position they indicate a later position on the motion trajectory. 
This interval between the actual and the perceived starting position 
is called the “Froehlich Effect”.

Selective attentional processes may explain this perceptual illusion: 
The stimulus onset elicits an attention shift towards the stimulus 
location. During the shift the stimulus moves further. Because the 
stimulus is not consciously perceived before the end of the focus 
shift, a later position is wrongly perceived as the first one.

If this explanation is valid, misperceptions should not be restricted 
to motion, rather they should also occur with any dynamically changing 
feature. Some experiments were conducted to inspect such new 
misperceptions for width and color. The results support the 
attentional account.