Participant performing the visual search task while walking on the GRAIL treadmill looking at the fixation cross. Stimuli were presented in the range from -40° to +40° degree visual angle and ...

Then, my heart skipped a beat as one of the satellites, at least that’s what I thought it was, made an abrupt right-angle turn, roughly two degrees of visual angle (the width of my thumb at arm ...

This article was originally published with the title “To Measure Distances by Visual Angles” inScientific American Magazine Vol. 10 No. 45(July 1855), p. 360doi:10.1038 ...