05. Sensation and Perception

Differentiate between sensation and perception

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• Define sensation and explain its connection to the concepts of absolute threshold, difference threshold, and subliminal messages

• Discuss the roles attention, motivation, and sensory adaptation play in perception

Explain the process of vision and how people see color and depth

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• Describe the basic anatomy of the visual system

• Describe how light waves enable vision

• Describe the trichromatic theory of color vision and the opponent-process theory

• Describe how monocular and binocular cues are used in the perception of depth

Explain the basics of hearing

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• Describe the basic anatomy and function of the auditory system

• Show how physical properties of sound waves are associated with perceptual experience

• Explain how we encode and perceive pitch and localize sound

• Describe types of hearing loss

Describe the basic anatomy and functions of taste, smell, touch, pain, and the vestibular sense

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• Summarize the chemical process of taste and smell

• Explain the receptors that respond to touch

• Examine the experience of pain, including how expectations and context affect pain and touch experiences

• Describe the basic functions of the vestibular, proprioceptive, and kinesthetic sensory systems

Identify examples of gestalt principles and multimodal perception

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• Give examples of Gestalt principles, including the figure-ground relationship, proximity, similarity, continuity, and closure

• Define the basic terminology and basic principles of multimodal perception

• Give examples of multimodal and crossmodal behavioral effects

• Explain how and why psychologists use illusions

• Examine applications of the Ebbinghaus illusion in the real world

Essential Concepts

Sensation and Perception

• Sensation occurs when sensory receptors detect sensory stimuli.

• Perception involves the organization, interpretation, and conscious experience of those sensations.

• All sensory systems have both absolute and difference thresholds, which refer to the minimum amount of stimulus energy or the minimum amount of difference in stimulus energy required to be detected about 50% of the time, respectively.

• Sensory adaptation, selective attention, and signal detection theory can help explain what is perceived and what is not. In addition, our perceptions are affected by a number of factors, including beliefs, values, prejudices, culture, and life experiences.

The Visual System

• Light can be described in terms of waveforms with physical characteristics like amplitude, frequency, and wavelength. A light wave’s wavelength is generally associated with color, and its amplitude is associated with brightness.

• Light waves cross the cornea and enter the eye at the pupil. The eye’s lens focuses this light so that the image is focused on a region of the retina known as the fovea. The fovea contains cones that possess high levels of visual acuity and operate best in bright light conditions. Rods are located throughout the retina and operate best under dim light conditions. Visual information leaves the eye via the optic nerve. Information from each visual field is sent to the opposite side of the brain at the optic chiasm. Visual information then moves through a number of brain sites before reaching the occipital lobe, where it is processed.

• Two theories explain color perception. The trichromatic theory asserts that three distinct cone groups are tuned to slightly different wavelengths of light, and it is the combination of activity across these cone types that results in our perception of all the colors we see. The opponent-process theory of color vision asserts that color is processed in opponent pairs and accounts for the interesting phenomenon of a negative afterimage.

• We perceive depth through a combination of monocular and binocular depth cues.

The Auditory System

• Sound can be described in terms of waveforms with physical characteristics like amplitude wavelength, frequency, and timbre.

  • Wavelength and frequency are inversely related so that longer waves have lower frequencies, and shorter waves have higher frequencies.

  • A sound’s frequency is associated with pitch, and its amplitude is associated with loudness.

• Sound waves are funneled into the auditory canal and cause vibrations of the eardrum; these vibrations move the ossicles. As the ossicles move, the stapes presses against the oval window of the cochlea, which causes fluid inside the cochlea to move. As a result, hair cells embedded in the basilar membrane become enlarged, which sends neural impulses to the brain via the auditory nerve.

• Pitch perception and sound localization are important aspects of hearing.

  • Our ability to perceive pitch relies on both the firing rate of the hair cells in the basilar membrane as well as their location within the membrane.

  • In sound localization, both monaural and binaural cues are used to locate where sounds originate in our environment.

• Individuals can be born deaf, or they can develop deafness as a result of age, genetic predisposition, and/or environmental causes.

  • Hearing loss that results from a failure of the vibration of the eardrum or the resultant movement of the ossicles is called conductive hearing loss.

  • Hearing loss that involves a failure of the transmission of auditory nerve impulses to the brain is called sensorineural hearing loss.

The Other Senses

• Taste (gustation) and smell (olfaction) are chemical senses that employ receptors on the tongue and in the nose that bind directly with taste and odor molecules in order to transmit information to the brain for processing.

• Our ability to perceive touch, temperature, and pain is mediated by a number of receptors and free nerve endings that are distributed throughout the skin and various tissues of the body.

• The vestibular sense helps us maintain a sense of balance through the response of hair cells in the utricle, saccule, and semi-circular canals that respond to changes in head position and gravity.

• Our proprioceptive and kinesthetic systems provide information about body position and body movement through receptors that detect stretch and tension in the muscles, joints, tendons, and skin of the body.

Perception and Illusions

• Gestalt theorists have been incredibly influential in the areas of sensation and perception. Gestalt principles such as figure-ground relationship, grouping by proximity or similarity, the law of good continuation, and closure are all used to help explain how we organize sensory information.

• Our perceptions are not infallible, and they can be influenced by bias, prejudice, and other factors.

Sensation and Perception Cheat Sheet from Lumen One Introduction to Psychology, Lumen Learning, https://lumenlearning.com/, CC BY.

Psychology, 2e, OpenStax, https://openstax.org/books/psychology-2e/, CC BY.

David Wiley