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Sensation and Perception. Visual Sensation in the Brain. Visual cortex-the brain transforms neural impulses into visual sensations like color, form, boundary and movement. Takes 2D patterns from each eye and assembles into 3D.
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Visual Sensation in the Brain • Visual cortex-the brain transforms neural impulses into visual sensations like color, form, boundary and movement. • Takes 2D patterns from each eye and assembles into 3D. • Takes sensations and combines them with memories, emotions, motives.
Visual System and Color • Physical objects have no color. • Color does not exist outside of the brain because color is a sensation that our brain creates based on the wavelength of light that reaches our eyes. • Color only exist in the mind of the viewer. • Visible spectrum-tiny part of electromagnetic spectrum we can see.
Sensing color • 2 ways of sensing color. • Trichromatic theory: 3 different types of cones sense different types of visible spectrum.(red, blue and green. • Opponent Process theory-The idea that cells in the visual system processes color in pairs or in the compliments. (red/green)
Sensation of Pitch • Sensory characteristics of sound produced by the frequency of the sound wave. • Place theory: different places on the basialiar membrane send neural codes for differnetpeitches to the auditory cortex of the brain • This is how we hear high tones.
Frequency theory: neurons on the basiliar membrane respond at different firing rates for different sound wave frequencies. • So the rate of firing produces another code for pitch perception in the brain.
Loudness and Timbre • Loudness: Sound produced by the amplitde of or intensity of a sound wave. • Measured in decibels • Timbre: the quality of the sound waves that derives form the complexity (combination of pure tones) • Example: A friend’s voice
Question? • If a tree falls in the forest, and there is no ear to hear it, is there a sound?
No, there is no sound because sound is not a physical phenomenon. • The sound of the tree falling produces vibrations in the air but there is no ear to produce a sound. • Sound is a psychological sensation that requires an ear to produce it.
Position and movement. • Vestibular sense: sense that orients us with respect to gravity. • Tells us when we are moving or how our motion is changing. • Very closely related to inner ear. • Disorders of this sense can cause extreme dizziness and confusion.
Kinesthetic sense keeps track of body parts relative to each other. • It provides constant sensory feedbackabout which muscles in your body are moving. • Both senses connect to the processing regions in the parietal lobe which helps make a sensory map in your brain.
Olfaction • Stimuls is sent to the olfactory bulbs where the sensation of smell are realized. • Has an inimate connection with memory. Certain smells evoke emotion lade n memories. • Pheromones: odorus signals meant to signal sex, danger and teritory present in animals. Evidence suggest also in humans for sex and recognizing family members.
Taste • Like smell it is base don chemistry • Gustation: means sense of taste like sweet, sour, bitter, and salty. • Umamai: flavor associated with monsodium glutamate used in Asian foods. Also in meats, seafood, and cheese. • Supertasters: more taste buds for bitter foods • Taste receptors are replaced
Skin senses • Sensory systems for processing touch, warmth, cold, texture and pain. • Plays a central in human relationships. • We communicate our desire to give/receive comfort, support, love and passion. • Primary stimulus for sexual arousal • Essential for healthy mental and physical development.
Finding Meaning in Sensation • Feature Detectors: cells in the cortex that especially sensitive to the features of the human face. • Binding problem: the process used to combine the results of many sensory operations into a single percept.
Ways of processing • Bottom Up Processing: emphasizes characteristics of the stimulus rather than our concepts and expectations. Also known as stimulus driven processing because it the percept is determined by the stimulus. • Example: What kind of salsa do we want?
Top down Processing • Occurs at the same time • Emphasizes the percieiversexpextatons, memories, past experiences, culutral background etc. • Known as conceptually driven processing. • Example: What kind of dog should I get?
Ambiguous Figures • Stimulus patterns that can be interpreted either top or bottom down. • Each example has 2 conflicting meanings. • Example: Necker cube
Explanations for Perception • Gestalt theory: We organize our incoming stimulation because of the way our brains are structured. • Emphasizes nature/genetics • Gestalt psychology: The brain forms a perceptual whole that is more than the sum of the sensory parts.
Learning Based Inference • Emphasizes how people use prior learning to to interpret new sensory information. • Founded by Hermann Helmholtz in 1866 • Nurture/experience • Example: we expect faces to look a certain way so when they don’t it violates our expectations.
