Sensation and PerceptionI. Sensation- stimulus detection process where our sense organs respond to and translatestimuli into nerve impulses sent to the brainII. Perception- active process of organizing stimulus input and giving it meaningIII. Stimulus Detection- How intense need to be for us to recognize its presenceIV. Absolute Threshold- the lowest intensity at which a stimulus can be detected at least 50% of the timeA. Just noticeable difference- the minimum change in a stimulus that can be detected1. At what level can you actually tell the difference in a stimulusB. Weber’s Law1. the difference threshold id directly proportional to the magnitude ofthe stimulus to which the comparison is being madeC. Fechner’s Law1. larger and larger increase in physical energy are required to produce equal increase in perceptionV. SensoryA. Signal Detection Theory1. various factors influence our sensory judgment2. often involves a process of decisions in addition to sensation 3 after watching a scary movie your more likely to hear noise around the house that were already thereB. Sensory adaption(habiutation)1. over time neurons decrease activity in response to a constant stimulus2. Constant stimuli overtime results in your stimuli to stoping..you used to the stimuli overtimeVI. Sensory Systems: VisionA. The normal stimulus for vision us electromagnetic energy or light wavesB. Light waves are measured in nanometersC. Our visual system is sensitive to wavelengths extending from ~700 nanometers(red) to ~400 nanometer (blue-violet)D. ROY G BIV (higher to lower wave lengths)VII. The Human EyeA. The waves enter the eye through the corneaB. The pupil: behind the cornea, the pupil adjust to control the amount of light that enters the eye fear also dilates the eyeC. The iris: The pupil’s size is controlled by muscles in the colored iris that surrounds the pupilD. low levels of light cause the pupils to dilate: allows more light and improves optical clarity E. Behind the pupil is the lens1. The lens becomes thinner to focus on distant objects2. The lens becomes thicker to focus on nearby objectsF. The lens focuses imagines onto the retina, reversing the imagine from right to left and from top to bottom: the brain reconstructs it into the imagine we perceive G. The retina contains specialized sensory neuronsH. The optic disk is a hole in the retina1. it yields a blind spot which we don’t experience as a hole as each eye compensates for the blind spot on the other2. The retina contains two types of light sensitive receptor cells rods and conesi. Rodsa. Function best in dim light, primarily black/ white brightness receptors, more sensitive to light than cones, no color sensation…black and white1) owls have ton or rods(night vision)ii. Conesa. function best in bright light, serve as color receptoriii. rods and cons translate light waves into nerve impulse which through the retinaa. These impulses pass through the optic disk and carry visual information from the brainb. They pass through the optic chiasm where the otic nerves from each eye cross over and pass information tothe opposite side of the brainI. Color VisionJ. Hue- commonly what is meant by color lengthK. Saturation- the color’s purity how dilated is it with black or whiteL. Color Theory1. Trichromatic Theoryi. three types of color receptors in the retina individual cones are most sensitive to either red, blue, or green, Couldn’t explainafter imaginesa. Flag example with doe that leaves an after imagine different form the original colors of the flag2. Color-Opponent Systemi. each system type of cone responds to two different wavelengths, re-green blue-yellow-, black-whiteii. different cones are receptors for different colors3. it takes both theories to explain color visioni. the eye has three types of cones with each being sensitive to adifferent band of wavelengths(trichromatic)ii. Cells have been found which respond in opposite ways to redv. green and blue v. yellow( Support opponent process)M. Infants are born with function/intact visual system, visual accommodationis not well developed. They focus on high contrast imagines and show a preference for facesVIII. Sensory Systems: hearingA. Audition: stimuli for hearing are sound wavesB. Frequency: the number of sound waves, cycles per second. Most common sounds are in lower frequenciesC. The quality of a tone from low to high, the number of times particles oscillate per second D. Complexity/Timbre: the wave purity or mixture of soundE. The Ear1. Sound waves travel into an auditory canal leading to the eardrum; a moveable membrane which vibrate in response to sound waves2. This leads to the middle ear. When the eardrum vibrates it sets in motion the hammer, anvil, and the stirrups( the smallest bonds in the human body) which amplify the sound waves3. The inner ear or the cochlea which is fluid-filled tunnel has tiny hairs or cilia’s which are the sound receptors. They move indifferent directions triggering the sensory neurons and an action potential 4. Temporal Code/Frequency Theory: nerve impulses sent to the brainmatch the frequency of the sound waves5. Place Code/ Place Theory: different areas of the basilar membrane are sensitive to different frequencies6. development of hearing: Research indicates the fetus can hear 3 months prior to birth7. Newborns have been shown to recognize books and voices and respond differentially to familiar voices and music8. Changes in sensitive to frequencies occurs as one ages. Older individuals are less sensitive to sounds at higher frequency(Mosquito Ringtone) IX. Sensory Systems: SmellA. Humans have ~10 million olfactory receptors (Schacter et al)B. The upper portion of the nasal passage detects smells which travel straightto the base of the brain at the olfactory bulb C. Pheremones-Chemical signals which are found in natural body scents in humans and other speciesX. Sensory Systems: TasteA . Four basic qualities of taste: sweet, sour, salty and bitterB. Umami has been identified as a 5th: savory meatyC Smell temperature and texture are all related to tasteD. Humans have about between 5000-10000 tatse budsE. taste buds can regenerate- but lose over timeF. Newborns prefer sweet to sour or butterG,. tatse preferences are largely learned and subject to cultural influencesH. Newer understanding of supertasters and on tasters based on density of taste budsI. Greater incidence of female supertastersXI. Sensory Systems: TouchA, Tactile Sensation: