Chapter 4: Sensations
Chapter 4: Sensations 1004
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This 5 page Class Notes was uploaded by rachel kelliher on Friday September 16, 2016. The Class Notes belongs to 1004 at Virginia Polytechnic Institute and State University taught by Benjamin DeVore in Fall 2016. Since its upload, it has received 7 views. For similar materials see Introduction to Psychology in Psychology (PSYC) at Virginia Polytechnic Institute and State University.
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Date Created: 09/16/16
[PP4: Sensation, 9/8/2016) ~Review Left brain= B and W areas- “we speak with the left brain” Difference between left and right brain= a lot of the questions ~Lecture Sensation= psychophysics o Studying physical energy that exists in the world that we are capable of converting to neuro energy o Receptors that convert physical to nero= very limited in humans o Number of noble prizes Buck and Axel & Georg von Bekesy= audition & Hubel and Wiesel= Vision General properties of the senses o Transduction- the process of converting one type of energy (any type of energy or stimuli) into another form of energy Occurs are the receptor- receptor converts physical energy to neural energy There are a variety of receptors in the body- pain, temp, color, etc Sensory receptors= limited- irritated/ triggered by only certain type of stimuli o “limited bandwidth or capacity Audition: 22kHz- the highest frequency that we can hear as humans Different species have higher frequencies- so we cant hear them AND they can hear higher frequencies then we can Olfaction: we can only smell certain things o Adaptation: Second property of receptors Threshold o Absolute threshold: min physical energy needed to activate a given sensory system 50% of the time Affected by deprivation, hormones, etc Combat setting vs training setting for military- draserically different Very dynamic- not a set value for anyone or a population Abs. threshold in low arousal state= drastically different then abs. in high arousal To commute it- the method of limits is used Ascending vs descending: o Ascending: intensity of light starts off low and increases o Descending: intensity of light starts off high (detected 100% of the time) and is lowered (detected 50% of the time) o Difference threshold: the difference between 2 stimuli required to distinguishes the difference from one stimuli from the other Related to abs. threshold 2 point threshold- helps determine how sensitive an area of the body is Senses o Vision Stiumuli= electromagnetic wavelength- rods and cods perceive 360nm (violet)- 760 nm (red) Eye anatomy Layers: o Outermost= sclera: tough protective layer- “like rubber” Modified at the front of the eyeball to create- cornea First prism system that is used to see images clearly o Middle= choroid Modified at the front of the eyeball to create the iris Iris has direct intervention via the PNS and SNS o PNS: pupillary constriction o SNS: pupillary dilation *ANS CONTROLS LENS AND IRIS VIA CRANICAL NERVES AND CIRCULATOIN* o 3 nerve= oculomotor= pupil dilation o Ciliopsinal reflex or budge= pupils dilate to pain no matter the source o Innermost= retina layer Where receptor cells from transduction environment-> neruo energy Modified at the front to form ciliary bodies Look like fingers that pull and stretch the zomula for near vision (within 18 inches of the eye) o Accommodation= stretching and pulling the zomula for near vision Ciliary bodies are responsible for it TEST QUESTION Loses elasticity overtime due to a variety of factors-> need for reading glasses Optic disk- at the back of the eye o Blind spit- very few receptors to transduce light here o Where the ganglion cells exit the eye Two types of receptors- Duplex retina o Cons) responsible for photopic light conditions- “fairly normal light conditions” Located primary in the back of the eyeball- fovea o Rods) scotopic light conditions- “near darkness conditions” Located primarily on the sides- peripheral of the eye Retina= inverted o Light goes through the cornea-> lens-> blood vessels-> ganglion cells-> bipolar and horizontal cells-> cones and rods (receptors) Optic pathway Each eyeball has two retinas- left brain retina and right brain retina o “two brains in each eyeball- R and L” Pathway enters eyes and eventually reaches occipital lobe Pituitary tumor causes gigantism-> tunnel vision o Taste= gustation Taste receptors are arranged on tongue in a certain way Change with development Receptors= everywhere: cheek, tongue, pharynx, larynx o Die off with age o Eventually leads to distribution of taste buds on the tongue Lots on sides, front and back of tongue- center= “largely devoid in the middle of the tongue” o 5 tastes: sweet, bitter, sour, salty, and umami Temperature impacts sensitivity to taste Metabolic theory/ hypo Temp and sense o Increase temp-> constant increase in salt o Increase temp-> gradual increase in bitter o Increase temp-> gradual decrease then rebound in sweet o Sour never changes As receptors die off the threshold double every 20 years Adaptation= aftertaste Electrical stimulation-> excites taste Tongue = lateralized like the brain Coding mechanisms o Retina= on and off coding o Contour coloring= lateral inhibition o Movement coding Stationary edge Moving edge Lights become dimmer, lights going off Spot moving acorss receptive field ~Diagrams