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Abstract

The experiment was designed to determine the ability of monkeys to visually discriminate the vertical from the non-vertical. Using a simultaneous, two-choice, non-correction technique in a WGTA, 8 mature, experimentally sophisticated monkeys were trained to respond to a vertical line and not to respond to a horizontal one. In the test sessions, the vertical line was randomly paired with 20 displacements (2° to 40°) from the vertical. The Kendall Coefficient of Concordance between 3 training measures and 2 test measures was significant (p < .001). The DL based on all test trials was 2°. The DLs for the first and second halves of the test sessions were 4° and 1°, respectively. There were large individual differences in the ability to make this discrimination, but after training, monkeys can discriminate less than 2° from the vertical.

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Difference Limen for Perception of the Vertical in Monkeys

Abstract

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