Chapter 5: Sensation and Perception
· Sensation: the process that detects stimuli from the environmentDon't forget about the age old question of Do you recapture depreciation on 1250 property?
· Perception: the process that organizes sensations into meaningful patterns
*Sensory ProcessesWe also discuss several other topics like Why does na+ enter the cell during the action potential?
· Stimulus/Stimuli: a form of energy that can affect sensory organs (ie: eyes or ears)
o Light or sound waves
o Starting point for sensation + perceptionWe also discuss several other topics like What metaphor best explains this theory?
· Sensation depends on specialized cells called sensation receptors: detect stimuli and convert their energy into neural impulses.
o This process is called sensory transduction
o Receptors serve our visual, auditory, smell, taste, skin, and body senses.We also discuss several other topics like What is the meaning of water balance in biology?
We also discuss several other topics like What is the difference between the old and new definition of mass media?
o Psychophysics: the study of the relationship between the physical characteristics of stimuli and the conscious psychological experiences that are associated with them
o Developed by Ernst Weber and Gustav FechnerWe also discuss several other topics like What does periphery mean?
o Absolute threshold: the minimum amount of stimulation that an individual can detect through a given sense
§ Varies depending on the sense
o Signal-Detection Theory: the theory that holds that the detection of a stimulus depends on both the intensity of the stimulus and the physical/psychological state of the individual.
o Response bias: how ready the person is to report the presence of a stimulus
o Researchers study 4 kinds of reports a person might make in response:
§ Hit: correct report of presence
§ Miss: failure to report when it’s present
§ False Alarm: report when nothing is present
§ Correct Rejection: correct report of absence
o Subliminal Perception: the unconscious perception of stimuli that are too weak to exceed the absolute threshold for detection
§ Debate arose in the 1950s
§ Meta-analysis of subliminal advertising studies found that its generally ineffective in influencing consumer choices
§ Audio “self-help” tapes
o Difference Threshold: the minimum amount of change in a stimulation that can be detected
§ i.e.: Volume
§ referred to by Weber and Fechner as ‘just notable difference’
§ must be a constant fraction of the original stimulus
· known as Weber’s Law
o Sensory Adaptation: tendency of sensory receptors to respond less and less to constant stimulus
§ i.e. how a house smells
§ lets us detect potentially important changes in an environment while ignoring unchanging aspects
· Vision: the sense that detects objects by the light reflected from them into the eyes
o Psychologists have conducted more research on this sense than all others
· Light Waves
o Visible Spectrum: the portion of the electromagnetic spectrum that we commonly call light
o Wavelength of light corresponds to is hue (the perceptual quality we call color)
§ Wavelength = distance between 2 wave peaks
o Violet corresponds to short wavelengths, red to long wavelengths
o Height/amplitude of a wave determines the intensity or a brightness of a light
o Purity of a wavelength determines its saturation
· Vision and the Eye
o Vision depends on the interaction between our eyes and our brain
o Parts of the eye:
§ Sclera: tough, white, outer membrane
§ Cornea: round, transparent area that lets in light
§ Iris: donut-shaped band of muscles behind the cornea; determines eye color
· Dilates to let more light in, constricts to let less light in
§ Lens: transparent structure behind pupil that focuses light onto the retina
§ Retina: light-sensitive inner membrane that contains the receptor cells for vision
· Image cast on the retina is actually upside down
· Contains specialized photoreceptors called rods and cones
· rods are especially important in night/peripheral vision
· cones important in colored/detailed vision
§ Optic Nerve: formed by the axons of ganglion cells that carry visual impulses from the retina to the brain.
§ Fovea: small area at the center of the retina that contains only cones and provides the most acute vision.