Psychology 100 Chapter 4 Sensation & Perception

Psychology 100 Chapter 4 Sensation & Perception

When the monster came, Lola, like the peppered moth and the arctic hare, remained motionless and undetected. Harold, of course, was immediately devoured. Chapter 4.2 October 8, 2014 Sensation and perception • Gustation • Olfaction • Haptic senses • Hearing • Vision Study Question: • Label diagrams of the following structures: The Ear, The Eye, The Tongue, Haptic Nerves, etc.

The simplified view Bitter Sour Salt Sweet Sensation • Taste • Qualitative information: • Sour • H+ ions block K+ channels • Sweet • Receptors that bind glucose • Salty • amiloride-sensitive Na+ channel • Bitter (G-Protein related) • Umami • metabotropic glutamate receptor (mGluR4)

Resiniferatoxin extracted from Moroccon spurge: 16 billion Scoville units Example Scoville units Pure capsaicin 15-16 000 000 Police grade 5 000 000 pepper spray Naga jolokia 1 000 000 Scotch bonnet 100k-350k habaneros Cayenne 30k-50k Jalepenos 2500-8000 Tobasco sauce Bell pepper 0 Sensation • Other Taste sensations • Temperature • False temperature • Cool (mint) • Heat (capsaicin) • Measured in Scoville units • Astringency (tannins) • Numbness • Sichuan pepper • Fat • CD36 protein

Sensation • Taste buds http://www.cf.ac.uk/biosi/staff/jacob/teaching/sensory/taste.html

Sensation • Taste buds • Range: 500 - 10,000 • Normal • 200 Fungiform + 1280 foliate + 2200 circumvallate = 3680 • Individual differences • Non-tasters (25%) • 117 papillae per cm2 • Normal (50%) • 127 papillae per cm2 • Super-tasters • 165 papillae per cm2

Sensation • Gustatory pathway • Three cranial nerves • VII (Facial Nerve) • Front/middle tongue • IX (Glossopharyngeal nerve) • Back of tongue • X (Vagus nerve) • Epiglottis and esophagus • Project to gustatory nucleus in the medulla

Sensation • Gustatory pathway • Thalamic relay • Ventral posterior medial nucleus (VPM) • Gustatory Cortex • Parietal Lobe • Insula & Frontal operculum

Sensation • Sense of smell • 100,000 unique odours • 80% are “noxious” • Organ of smell • Olfactory epithelium - thin layer within the nasal cavity embedded with receptors • Size is proportionate to olfactory acuity. • Humans -> 10 cm2 • Dogs -> 170 cm2 -> Also have 100x as many receptors per cm2

Sensation • Sense of smell • Receptors • Are also neurons • Coalesce to form Olfactory nerve • Cranial nerve I • Project to olfactory bulb • To amygdala, frontal cortex

Sensation • Haptic Sense • Main sensations • Pressure • Temperature • Pain • Position • Other Candidates • Vibration, tickle and itch

Sensation • Hapic sense • Receptors • Mechanoreceptor - haptic receptor that responds to mechanical pressure or distortion • Four different types + hair follicle receptor • Thermoreceptors - haptic receptors in our skin that can perceive changes in temperature • as small as 0.01C • Proprioceptors - haptic receptors that determine body position. • Where + direction & speed of movement. • Receptors in the skeletal muscle

Sensation • Pain • Types of Pain fibers • A-Delta fibers: Convey the sharp immediate pain of injury. • C fibers: Convey slow, dull, burning pain that lingers after injury.

Ronald Melzack (b. 1929) Sensation • Pain • Gate control theory • There is a gateway for pain located in the midbrain. • The periaqueductal gray (PAG) contains neurons that inhibit cells carrying pain signals to the brain. • Role of Endorphins

High Compression Low Sensation • Hearing • The physical stimulus • The quantitative element • Amount of compression (sound pressure). • We hear loudness, measured in decibels.

Quantitative Loud Soft Low Qualitative High Sensation • Hearing • The physical stimulus • The qualitative element: • Frequency of compression waves. • We hear pitch

Sensation • Hearing

Sensation • Coding for pitch • Place theory • Frequency is determined by the place on the basilar membrane where there is maximal vibrational amplitude. • Two forms of deafness • Conduction • Nerve • Problems with place theory • Volley theory • Receptors work together to register higher frequencies

Sensation • Vision • The Physical Stimulus

Sensation Sensation • Vision • The eye

Sensation • Vision • The retina

Sensation • Vision • Rod and cone vision • Cones (6 million) • Specialized for colour and acuity • concentrated in fovea • Rods (120 million) • Specialized for sensitivity in dim light • concentrated in periphery • Both contain a photochemical (in the rods: rhodopsin) • Two reasons why rods are more sensitive to light • Rhodopsin is more sensitive to light • Higher number of rods per ganglion cell

Sensation • Vision • Colour Vision • The colour of objects is determined by pigments • Pigments absorb certain wavelengths • Colour perception occurs through subtraction • Subtractive colour mixing

Sensation 700 600 500 400

Sensation • Vision • Additive Colour Mixing • When coloured lights are mixed, two laws apply: • Three Primaries Law • Law of Complimentarity

Sensation • Vision • Additive Colour Mixing

Sensation • Vision • Two Theories of colour vision • Trichromatic theory • three types of receptors are sufficient for colour perception

Sensation • Vision • Two Theories of colour vision • Trichromatic theory • RGB Monitors

Sensation • Vision • Two Theories of colour vision • Opponent Process theory • Trichromatic theory does not account for complimentary colours. • Colour vision is mediated by cells that can be excited or inhibited • Blue- Yellow, Red - Green, & brightness

Sensation • Vision • Two Theories of colour vision • Opponent Process theory

Sensation • Vision • Coding of Contrast and Contour • Illusory Contour

Sensation • Vision • Coding of Contrast and Contour • Exaggerated Contrast

Sensation • Vision • Feature detectors • Hubel and Weisel • Simple cells - edge detectors • Complex cells - edges at particular angles • Hypercomplex cells - angles and length • Higher level feature detectors: Motion detectors • Spiral after effect

Psychology 100 Chapter 4 Sensation & Perception