Sensation & Perception Unit 3 Chapter 4

Sensation Stimulation of sensory receptors and transmission of sensory info to the central nervous system (spinal cord/brain) Stimulation of sensory receptors and transmission of sensory info to the central nervous system (spinal cord/brain) –Sensory receptors –Stimulation automatic –Presence of chemicals

Absolute Threshold Weakest amount of stimulus that can be sensed Weakest amount of stimulus that can be sensed Vision, hearing, smell, taste, touch Vision, hearing, smell, taste, touch Differ from person to person Differ from person to person –Psychological factors –Biological factors

Examples of Absolute Thresholds SenseAbsolute Threshold Vision A candle flame seen at 30 miles on a dark clear night Hearing The tick of a watch under quiet conditions at 20 feet Taste One teaspoon of sugar in two gallons of water Smell One drop of perfume diffused into entire volume of a six room apartment Touch The wing of a fly falling on your cheek from a distance of 1 centimeter

Difference Threshold Minimum amount of difference detected between 2 stimuli Minimum amount of difference detected between 2 stimuli

Signal-Detection Theory Method for distinguishing sensory stimuli that accounts for stimuli strengths, and setting, your physical state, your mood, your attitude Method for distinguishing sensory stimuli that accounts for stimuli strengths, and setting, your physical state, your mood, your attitude Also considers psychological factors Also considers psychological factors –Motivation –Expectations –Learning

Perception Psychological process through which we interpret sensory stimulation Psychological process through which we interpret sensory stimulation Reflects learning, expectations, attitudes Reflects learning, expectations, attitudes Way in which we organize our sensory information Way in which we organize our sensory information

Closure Tendency to perceive a complete or whole figure even when there are gaps in what your senses tell you Tendency to perceive a complete or whole figure even when there are gaps in what your senses tell you Fill in the blanks Fill in the blanks

Ground-Figure Perception Figures against a background Figures against a background What we perceive as figure and what we perceive as background influence our perception What we perceive as figure and what we perceive as background influence our perception

Proximity Group together events that are near each other Group together events that are near each other Things which are close together are seen as belonging together Things which are close together are seen as belonging together

Continuity Perceive things as belonging together if they form some type of continuous pattern Perceive things as belonging together if they form some type of continuous pattern

Similarity Occurs when objects look similar to one another Occurs when objects look similar to one another See groups which have the same characteristics See groups which have the same characteristics

Common Fate Tendency to perceive objects that are moving together as belonging together Tendency to perceive objects that are moving together as belonging together

Depth Perception Monocular Cues Need only one eye to be perceived Need only one eye to be perceived Cause certain objects to appear more distant from the viewer than others Cause certain objects to appear more distant from the viewer than others pictorial depth cues- pictorial depth cues- clues about distance given in a flat picture Binocular Cues Visual cues for depth that require the use for both eyes Visual cues for depth that require the use for both eyes retinal disparity- images projected to different locations on right and left retinas retinal disparity- images projected to different locations on right and left retinas convergence- sensing the eyes converging toward each other as they focus on closer objects convergence- sensing the eyes converging toward each other as they focus on closer objects

Stroboscopic Motion illusion of movement illusion of movement rapid progression of images or objects not moving at all rapid progression of images or objects not moving at all our perceptions our perceptions fill in the gaps fill in the gaps

Stroboscopic Photography

Vision Unit 2.2

The Human Eye cornea- transparent tissue where light enters the eye cornea- transparent tissue where light enters the eye pupil- opening in center of iris that allows light to pass into the eye pupil- opening in center of iris that allows light to pass into the eye iris- controls pupil size iris- controls pupil size lens- focuses the light rays on the retina lens- focuses the light rays on the retina retina- contains sensory receptors that process visual information and send it to the brain retina- contains sensory receptors that process visual information and send it to the brain optic nerve- carries visual info to brain optic nerve- carries visual info to brain

Near + Far Nearsightedness Nearsightedness –Close objects are seen clearly but distant objects appear blurry –Eyeball is too long Farsightedness Farsightedness –Distant objects seen clearly but close objects appear blurry –Eyeball is too short

Rods and Cones 2 kinds of photoreceptors 2 kinds of photoreceptors –Neurons that are sensitive to light Rods are sensitive to only brightness Rods are sensitive to only brightness –Allow us to see black/white Cones provide color vision Cones provide color vision

Dark and Light Adaptation Dark- adjustment to lower lighting Dark- adjustment to lower lighting –Continues to improve for up to 45 minutes Light- adjustment to bright lighting Light- adjustment to bright lighting –Occurs within minutes

Visual Acuity Sharpness of vision Sharpness of vision Determined by ability to see visual details Determined by ability to see visual details

Color Vision Cones enable us to perceive color Cones enable us to perceive color –Sensitive to blue, green, red Multi cone stimulation allows for other colors to be seen Multi cone stimulation allows for other colors to be seen –Other colors are created through combinations of red, blue, green

Color Compliment Afterimage of a color is its complimentary color Afterimage of a color is its complimentary color

Color Blindness People who don’t have normal color vision People who don’t have normal color vision Partially or totally unable to distinguish color Partially or totally unable to distinguish color –Malfunction of cones Total color blindness is rare Total color blindness is rare –Sensitive to only light and dark Partial color blindness is more common Partial color blindness is more common –See red green but have hard time distinguishing between the two

Depth Perception Monocular Cues Need only one eye to be perceived Need only one eye to be perceived Cause certain objects to appear more distant from the viewer than others Cause certain objects to appear more distant from the viewer than others Perspective, clearness, shadow Perspective, clearness, shadow Binocular Cues Visual cues for depth that require the use for both eyes Visual cues for depth that require the use for both eyes retinal disparity- depth of an object retinal disparity- depth of an object convergence- both eyes focus on the same object convergence- both eyes focus on the same object

Hearing Unit 2.4

The Ear  Outer ear- collects and sends sounds to the eardrum  Cochlea- transforms sound vibrations to auditory signals  Auditory nerve- transmits neural impulses to brain

Deafness Conductive  damage to middle ear  Affects sound amplification  Can be corrected with hearing aids Sensorineural  Damage to inner ear, auditory nerve  Absence of sound perception for certain frequencies  “artificial ear”

Other Senses Unit 2.5

Smell  Essential to taste  Odors are detected by receptor neurons in nostrils  React when molecules come into contact with them  Send information about odor to brain via olfactory nerve  Adapts quickly

Taste  Sweet, sour, salty, bitter  Flavor of food is more complex than taste  Odor, texture, temperature, taste  Receptors on taste buds of tongue  Sensitivity to different tastes can be inherited  Bitter = “taste blind”  Taste cells reproduce rapidly

Skin Senses (Touch)  Combination of pressure, temperature, pain  Distinct sensory receptors  Receive more than one type of sensory input

Pressure  Sensory receptors (pacinian corpuscle) located around the roots of hair cells  Fire where skin is touched  Different parts of body more sensitive  more = fingertips, lips, nose, cheeks  less = shoulders, thighs, calves  Rapidly adapts

Pain  Receptors located all over body  Not all equally sensitive to pain  prostaglandins- help body transmit pain messages to brain  Can experience pain in limbs no longer there = “phantom limb” Message sent to spinal cord to thalamus in brain Projected to cerebral cortex where registration of severity/location of pain is determined Pain originates at the point of contact

The Gate Theory of Pain Only a certain amount of information can be processed by the by the nervous system at one time Different sensations compete with pain messages for attention Neurons cant get pain messages to brain “Flooding” prevents many or all messages from getting through

Body Senses  Vestibular- position of the body  sensory organs located in the ears  Enables balance  Kinesthesis- position and movement of individual body parts  Sensory organs in joints, tendons, muscles