Psychophysical Model of the Signal Detection Theory in the Categorization Task of Textual and Pictographic Visual Stimuli

A number of studies showed that the form of presentation of the stimuli affects the perception of these stimuli and their processing by the brain. In categorization tasks, the processing of stimuli of different categories in visual and verbal forms was compared. However, the mechanisms of categorization of stimuli of various forms and categories require additional research. The paper considers the application of the psychophysical model of signal detection theory (SDT) to the problem of categorizing textual and pictographic visual stimuli. SDT is used to measure sensitivity, biases and discriminability performed in categorization tasks. An experimental study involved 55 participants (14 males aged 18 to 23 years and 41 females aged 18 to 24 years). Stimulus material was developed by the authors of this study and consisted of two recognizable natural categories of objectified nouns: fruits and dishes. Graphical stimulus material was presented in the form of pictograms. Each category consisted of eight objects, so a total of sixteen words (names of the objects) and sixteen corresponding pictograms were selected. Pictographic stimuli were categorized faster than textual stimuli. However, the ability to recognize text was higher than the ability to recognize pictograms. When making a categorization error, most of the subjects demonstrated liberalism. SDT has shown its productivity in assessing discriminability of visual stimuli and expanded our knowledge of categorization mechanisms.