Introduction to Psychology Sensation & Perception
Jan 21, 2016
Introduction to Psychology
Sensation & Perception
Sensation v. Perception
Sensation: the stimulation of sensory receptors; neural signals from environmental stimuli (neural process) The process of conversion between physical
energy (i.e. light) into neural impulses is called transduction
Perception: the process of apprehending, recognizing, understanding, and learning of environmental stimuli (cognitive process)
Psychophysics
Psychophysics: the study of the relationship between physical stimuli and the behavior or cognitive experiences which they evoke
Absolute Threshold: the minimum amount of physical energy needed to produce a sensory experience (neural impulse)
Difference Threshold: The smallest physical difference between two stimuli that can still be recognized as a difference.
Sensory Adaptation (habituation): the diminishing responsiveness of sensory systems to prolonged stimulus input
Sensitization: prolonged sensory input increases or amplifies a response
Sensation & Perception: Vision
Sensation & Perception: Vision
Retina: the inside covering of the eyeball where images from the lens project Full of neurons called photoreceptors
Rods: work best in low light; sees edges Cones: works in brightness; sees color
Sensation & Perception: Vision
Sensation & Perception: Vision
Sensation & Perception: Vision
Sensation & Perception: Vision
Sensation & Perception: Vision
Face Perception
Nuanced facial perception is typically associated with a place in the brain referred to as the Fusiform Face Area (FFA)
Located on the ventral surface of the temporal lobe
Damage to the FFA results in Prosopagnosia or “face blindness”
People are typically very good at recognizing faces……almost too good
Faces in weird places (i.e. toast)
Sensation & Perception: Vision
Sensation & Perception: Vision
Depth Perception
The ability to view the world in three dimensions and to perceive distance
Occurs through processing the difference (Binocular Disparity) between the images seen by the right and left eyes
Depth perception and the fear of heights is acquired in infancy through experience
https://www.youtube.com/watch?v=p6cqNhHrMJA
Sensation & Perception: Vision
Color blindness: there are 3 types of cones; when a person lacks one or more types of cones they see the world differently Some animals have more kinds
of cones and can see different wavelengths of color
Qualia: is a term used in philosophy to refer to individual instances of subjective, conscious experience.
Is my red the same as your red? Do I taste the same as you do?
Sensation & Perception: Vision
Sensation & Perception: VisionMantis Shrimp have 12 types of photoreceptors and can see much more of the light spectrum than humans (with our measly 3 photoreceptors).
Mantis Shrimp must think we look really boring!
Sensation & Perception: Vision
Blindness https://www.youtube.com/watch?v=ZDHJRCtv0WY https://www.youtube.com/watch?v=919GzqpFDBk
Sensation & Perception: Auditory
Sound: The movement of air particles brought about by some source of vibration
This vibration is sensed by various structures within the ear Eardrum (Tympanic Membrane) Tiny bones in the middle ear
Hammer, Anvil, & Stirrup Cochlea
Basilar membrane Hair cells
Sensation & Perception: Auditory
Sensation & Perception: Auditory
Sound localization: 2 ears allow organisms to locate the origin of sound in the environment Relative timing Relative intensity
Sensation & Perception: Olfaction
Sensation & Perception: Gustation
Both olfactory and gustatory receptors are chemoreceptors. Smells are through distance chemoreceptors Tastes are through direct chemoreceptors
Taste buds on the tongue are bundles of chemoreceptors
Taste buds are also located on the roof of the mouth and interior cheeks, just in less density.
Touch, Vestibular, & Kinesthetic Senses
Touch (cutaneous [skin] senses) Include touch, pressure, temperature, and pain Sensitivity based on the density of nerve fibers and
sensory cortex allocated to that area Includes pressure and temperature
Vestibular Senses your orientation in the world with respect to
gravity Information comes from the inner ear People with vestibular issues may have vertigo
Kinesthetic Sensory feedback for motor activities
Sensation & Perception: Pain
Pain: body’s response to stimuli that cause or threaten to cause tissue damage; includes: Temperature Mechanical Chemical
Pain is (somewhat) subjective and can be moderated by a variety of factors: Conflicting or distracting stimuli Holding hands with a loved one
Intersensory Redundancy
Intersensory Redundancy occurs when multiple senses contribute to one synchronous experience
Intersensory redundancy occurs with amodal properties of stimulation (tempo, intensity, frequency)
Intersensory redundancy recruits attention and promotes learning and memory
Our reality is constructed with redundant stimulation
Infants can perceive events as synchronous even if they are offset considerably (700ms); the window of synchrony narrows in adulthood (300ms)
When sensory experiences are out-of-sync, attention learning becomes difficult and frustrating
Out of sync movie
Intersensory Redundancy
Problems can occur when there is conflicting stimulation from multiple senses
The McGurk Effect occurs when a sound does not match the facial movements of the person speaking The more “dominant” sense (in this case vision) wins
out over the other (auditory), and perception of the stimuli changes
https://www.youtube.com/watch?v=G-lN8vWm3m0
Perceptual Narrowing
Perceptual Narrowing is a sensory attunement process that helps organisms “hone in” on native stimuli, while ignoring irrelevant or improbable stimuli
Early in development, neurons are pruned from sensing environmentally rare stimuli and recruited for making nuanced distinctions for relevant stimuli
Needs to happen for the organism to function in it’s particular environment
Perceptual narrowing occurs as soon as senses “come online” and works extremely quickly; most sensitivity to non-native stimuli is lost within the first year
Can inadvertently contribute to ethnocentrism and racism
Has implications for: Language processing Facial recognition Taste
Perceptual Organization
Top-Down processing Perception is guided by higher-level
knowledge, experience, expectations, and motivations
Bottom-Up processing Perception consists of the progression of
recognizing and processing information of individual components of a stimuli and moving up to the perception of the whole
Perceptual Organization
Perception and Perspective https://www.youtube.com/watch?v=hCV2Ba5wrcs
Perceptual Constancy
Perceptual Constancy The phenomenon in which physical objects
are perceived as unvarying and consistent despite changes in their appearance or in the physical environment
Piaget (cognitive perspective) demonstrated how object permanence and perceptual constancy develops in childhood
https://www.youtube.com/watch?v=gnArvcWaH6I
Other Sensory Disorders
Anesthesia: Lack of sensation, lack of consciousness
Synesthesia: stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory process https://www.youtube.com/watch?v=BWGNWgBk76k