visual agnosia

loss or impairment of the ability to recognize and understand the nature of visual stimuli. Classically, a distinction between apperceptive and associative forms of visual agnosia has been made. Individuals with the former are said to have deficits in the early stages of perceptual processing, whereas those with the latter either do not display such problems or do so to a degree not sufficient to substantially impair the ability to perform perceptual operations. Subtypes of each form exist based on the type of visual stimulus the person has difficulty recognizing, such as objects (visual object agnosia or visual form agnosia), multiple objects or pictures (simultanagnosia), or colors (color agnosia). See also integrative agnosia; prosopagnosia.

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Psychology term of the day

January 19th 2025

pretest

1. n. an initial assessment designed to measure existing characteristics (e.g., knowledge, ability) before some intervention, condition, manipulation, or treatment is introduced. Pretests often are given to research participants before they take part in a study. For example, in a study examining whether training helps math performance, participants might be administered a short math test to assess their original knowledge prior to undergoing the training. See also posttest.

2. n. a test administered before the main study to ensure that participants understand the instructions and procedures. See pilot study; practice trial.

3. vb. to administer a pretest.