In Experiment 1, stimuli were straight lines with a deviation or ‘kink’ at their midpoint (indicated by white vertical markers). Observers had to indicate the direction of deviation as either ‘upwards’ (panels A and B) or ‘downwards’ (C and D). The parameters that were varied were line length and blur. In Experiments 2 and 3, stimuli were ‘blobs’, which moved rightwards on a linear path with a certain velocity until the midline, at which stage a deviation in the trajectory occurred. Observers again had to signal the direction of deviation. The lines in panels A-D can be considered as a schematic representation of the path traced out by the moving blobs. For the moving stimuli, path length, stimulus blur and viewing distance were varied.