PSYC 1010 Lecture 4: Chapter 4

• School: York University
• Department: Psychology
• Course: PSYC 1010
• Professor: Myriam Mongrain

Document Summary

Chapter 4 sensation & perception: gustav fechner was an important contributor to psychophysics. psychophysics the study of how physical stimuli are translated into psychological experience. When lights of varying intensity are flashed at a subject, there is no single stimulus intensity at which the subject jumps from no detection to completely accurate detection. Instead, as stimulus intensity increases, subjects" probability of responding to stimuli gradually increases: a just noticeable difference (jnd) is the smallest difference in the amount of stimulation that a specific sense can detect. An absolute threshold is simply the just noticeable difference from nothing (no stimulus input). Jnds vary by sense, and the smallest detectable difference is a fairly stable proportion of the size of the original stimulus. Weber"s law states that the size of a just noticeable difference is a constant proportion of the size of the initial stimulus. This constant proportion is called the weber fraction.