Alphabet and grammar in visual search

A quantitative analysis was made to clarify the ability of human observers to detect a line of a unique orientation against a background of lines of a different orientation. Results of a psychophysical experiment indicated that the performance of correct judgments increased with the number of adjacent lines under the control of lateral masking effects. A model for decision making was formulated to simulate the results. The consistence between the experiment and the simulation suggested; (1) the human visual system uses differences between adjacent lines of orientations, (2) it integrates the orientation differences into a global percept by the Bayesian inference rule.<>