In terms of perception, constancy refers to the capability of one or more perceptual systems to identify the same object among a sea of sensory inputs. For example, a coin looks circular when held face-on, and elliptical when it is held showing its side. But, constancy enables us to identify the object as a coin even if it is held either way. Without constancy, we might perceive one object as a different sensory input if sensed in a different angle, degree, intensity or frequency.
There are various kinds of constancy. One type is called color constancy major focus in the field of perception. For instance, a white paper is normally perceived as "white" even under varying intensities and colors of light. Others include odor, melody, brightness, words, and roughness. The kind of information being perceived is identified by the brain first before the perceptual systems achieve the corresponding perceptual constancy.
Grouping is a feature of perception that follows the principles primarily proposed by Gestalt psychologists. The principles of grouping were formulated to analyze the natural human perception of objects as organized and in patterns. The six Gestalt grouping principles include proximity, similarity, closure, good continuation, common fate, and good form. Learn more about them here.
A contrast effect refers to the increase or decrease in perception as related to the normal intensity, degree, frequency or other attributes. The so-called "normal perception" is based on the previous experience/s of the person.
John Locke, a 17th century philosopher, was among the earliest scholars who observed the contrast effect. Suppose that you touch cup A with hot water. According to him, lukewarm water in cup B can be perceived as "hot". But, the lukewarm water would feel "cold" if your hand had previously touched a cup with cold water. Many years later, Wilhelm Wundt stated that contrast is a basic principle of perception. For proper contrasts, the objects being compared must be similar to each other. Since the early 20th century, researchers have performed several observations to confirm contrast effects. One research on the perception of music revealed that subjects would identify a song as "good" or "bad" depending on how the previously heard music is subjectively "good" or "bad". The effects of the contrasts influence visual qualities such as brightness and color, as well as other precepts like weight and lightness.
This means you're free to copy, share and adapt any parts (or all) of the text in the article, as long as you give appropriate credit and provide a link/reference to this page.
That is it. You don't need our permission to copy the article; just include a link/reference back to this page. You can use it freely (with some kind of link), and we're also okay with people reprinting in publications like books, blogs, newsletters, course-material, papers, wikipedia and presentations (with clear attribution).