Sensation and Perception Argumentative

            The term sensation refers to the initial detection of energy from the physical world and is studied, in detail, by specialists in psychophysics. The study of perception generally deals with the structure and processes of the sensory mechanism and the stimuli that affects those mechanisms. Sensation refers to the initial detection of the stimuli which is caused by touching, seeing, smelling, hearing, or tasting. (Solso,1995, p.66, )

            The term perception, on the other hand, involves higher-order cognition in the interpretation of the sensory information. (Solso, 1995, p. 66)

            Perception is not sensation,  Perception is sensation plus interpretation. When an information is sensed by a person, that information is transmitted to the brain for interpretation.(http://io.uwinnipeg.ca/~epritch1/sensperc.htm)

             Thus, perception refers to an interpretation of the things we sense.

            Perception is best illustrated through the use of illusions, such as the Müller-Lyer illusion or the  Ponzo illusion in which two equal segments of a line seem unequal. Illusions are partly influenced by our past experiences or previous knowledge of the world, though, some would argue that these illusions reflect abstruse invariant structures of the brain. (Solso, 1995, p.67)

            Depth perception can be used in two ways. In one case, the term refers to the distance from the observer to an object. This is sometimes called the absolute distance. Alternatively, it may also refer to the distance between one object and another or between different parts of a single object. This is known as relative distance. (Sekuler, Blake, 1994, p.216) In using the Müller-Lyer illusion or the Ponzo illusion to illustrate depth perception, the perspective cues in these illustrations imply that one region of the figure is farther away than the other. (Sekuler,Blake, 1994, p. 247). Also, when one object partially covers the other, we perceive that the object that is partially covered must be at a greater distance than the object that is covering it. This situation, which is called occlusion, is a signal or cue, that one object is in front of the other. The connection between cue and depth is learned through our previous experiences with the environment. (Goldstein, 2007, p. 168)

            Perception in motion also involves processes that depend on the observer’s past experiences. There are a number of different ways to achieve the perception of motion. For example, when an object moves across an observer’s field of view, this is called real movement because the object is physically moving; when an observer is presented two stationary stimuli, one after another, in slightly different locations, it can cause the perception of movement between these stimuli, and this is called apparent movement because there is no actual or real movement;  when a movement is an illusion because the observer perceives a movement even though a stimuli is not moving, such as a moon racing through the clouds on a windy night where the moon is actually stationary but the moving clouds make it appear to be moving, this is called as induced movement; and, when a movement occurs after viewing a stimulus and then seeing a movement in the opposite direction when viewing a stationary stimulus, this is called as movement aftereffects. (Goldstein, 2007, p.  196)

            Perception constancies may refer to color, lightness, odor, shape, size and speech. In color constancy,  an object’s color tends to remain constant even though the spectrum of light falling on that object changes the light that is reflected toward the observer of that object. (Sekuler, Blake, 1994, p.188) In lightness constancy, the observer’s perception of lightness remains constant despite viewing an object under different levels of light. Lightness constancy works and keeps the observer from erroneous interpretation of what he is seeing for it allows recognition of an object even when the level of illumination changes drastically. (Sekuler, Blake, 1994, p. 81) Under odor constancy, an observer perceives the strength of odor to remain constant despite variations of the flow rate towards the olfactory system. ( Sekuler, Blake, 1994, p. 431) Shape and size constancies are  where the observer still tends to perceive the shape and size of the object as constant in the face of an altered retinal image or differences in distances from the observer and the object. In speech constancy, the observer tends to still recognize speech in the face of the invariability in the acoustic signal caused by co-articulation, different speakers, and sloppy pronunciation.(Goldstein, 2007, p.291)

            Perception constancies help as respond to a given situation in the light of our past experiences and knowledge on the situation. Our view point towards the object remains constant despite the alterations made on that object by our surroundings, thus helping as tell the differences between what our senses detect and how we are to interpret it.

References

Goldstein, E. Bruce (2007)    Sensation and Perception

            7^th Edition,

            Thomas Wadsworth

Sekuler, Robert, Randolph Blake (1994)  Perception

            3^rd Edition

            McGraw-Hill International Editions

Solso, Robert L. (1995)  Cognitive Psychology

            4^th Edition

            Allyn and Bacon

http://io.uwinnipeg.ca/~epritch1/sensperc.htm