Tapered dipoles in briefly flashed Glass-pattern sequences disambiguate perceived motion direction

In order to investigate the relationship between 'neural speedlines', form (shape), and fast motion-direction decisions, Glass patterns were constructed with dipoles assuming a tapered shape. The results of a 2-alternative forced-choice direction-discrimination task, for both concen- tric and translational Glass-pattern sequences, suggest that with short stimulus presentations (<1 s) form can influence direction decisions. This result implies that neural speedlines may be analogous to tapered lines and further supports Geisler's (1999, Nature 400 65-69) model of form/motion interaction.