Frontiers in neuroscience
Landolt C acuity follows Bloch's Law for short-duration flashes
By Ketz CC, Bach M and Heinrich SP.
Abstract
Purpose
Bloch's Law states that up to a critical duration, typically between 30 and 100 ms, the detection of a flash depends on its total strength (the product of luminance and duration). This study investigated whether this principle of temporal summation extends to shape recognition, assessed via optotype-based visual acuity.
Methods
Monocular Landolt-C acuity was measured in 19 healthy participants across 25 stimulus conditions. These conditions combined five photopic luminance levels (3.3-53 cd/m2) with five presentation durations ranging from 0.125 to 512 ms. The combinations were grouped into five flash strength levels, spanning a 256-fold range from 6.7 to 1,708.2 cd · s/m2 × 10-3.
