Lecture 12 - Chapter 6 PDF

Lecture 12 – Chapter 6 Dr. Christie Tetreault [email protected]  Sensation and Perception  Sensation  awareness resulting from the stimulation of a sense organ  Perception  the organization and interpretation of sensations.  Sensation and perception work...

Lecture 12 – Chapter 6 Dr. Christie Tetreault [email protected]  Sensation and Perception  Sensation  awareness resulting from the stimulation of a sense organ  Perception  the organization and interpretation of sensations.  Sensation and perception work so we can:  sense our environment  combine what we are currently learning from the environment with what we already know  so we can make judgments and to choose appropriate behaviours.  Six senses: seeing, hearing, smelling, touching, tasting, monitoring body’s positions  Transduction  the conversion of stimuli detected by receptor cells to electrical impulses that are then transported to the brain  What can we experience  Human eye can detect 300,000 colours  Human ear can detect sounds as low as 20 hertz and as high as 20,000  Human tongue can taste a tsp of sugar in 7 liters of water  Human nose can smell one drop of perfume diffused into a three-room apartment  Skin can feel a wing of a bee 1 cm away from our cheek  WE ARE SENSTIVE but….  Other animals sense a lot more  Other animals have better hearing, sense of smell, sight  Some can even sense the earth’s magnetic field  Many animals can function better in darkness than humans  Why??  Each species is adapted to sensing the things that are most important to them and can weed out things that don’t matter  How do we measure sensation?  Psychophysics  the branch of psychology that studies the effects of physical stimuli on sensory perceptions and mental states  Fechner was the first to study this  T heir techniques were to determine the limits of human sensation  Absolute threshold of a sensation  the intensity of a stimulus that allows an organism to just barely detect it The basics:  Say yes if the sounds is there, say no if the sound is not there Easy?  not exactly  When it’s so faint, your senses can trick you into thinking something is there when it isn’t, and that something isn’t there when it is  Signal detection analysis  a technique used to determine the ability of the perceiver to separate true signals from background noise  4 outcomes  Hit(says yes when there is a sound)  Falsealarm (say yes but no sound)  Miss (say no but there is a sound)  Correct rejection (say no when there is no sound)  Measuring Two measures  Sensitivity  true ability of the individual to detect the presence or absence of signals  Response bias  behavioural tendency to respond “yes” to the trials, which is independent of sensitivity  In some situations, a slight response bias may be better than a miss  Ability to assess differences between  The difference threshold (or just noticeable difference [JND])  the change in a stimulus that can just barely be detected by the organism  Weber  made an important discovery about JND  Ability to detect differences depends on the size of the difference in relation to the absolute size of the stimulus  Adding a tsp of sugar to a coffee that has little sugar in it already versus adding a tsp of sugar to a coffee already with 5 tsp of sugar  That is called Weber’s law  just noticeable difference of a stimulus is a constant proportion of the original intensity of the stimulus  Conscious vs subliminal  A stimulus is conscious when it can be accurately reported on its existence more than 50% of the time  Subliminal stimulus  events that are below the absolute threshold and which we are not aware of them  Subliminal advertising?  No, not evidence-based  Blindsight (damage to specific areas in visual cortex)  a condition in which people are unable to consciously report on visual stimuli but can accurately answer questions about what they are seeing (brain is processing more than we’re aware of)  How do we see  Electromagnetic energy  pulses of energy waves that can carry information from place to place.  Electromagnetic waves vary in their:  wavelength  the distance between one wave peak and the next wave peak  shortest are gamma  a fraction of a millimeter in length  longest are radio  hundreds of kilometers long.  amplitude  distance between the resting position and the maximum displacement of the wave (height of the wave)  frequency  number of waves passing by a specific point per second  Our eyes detect only the range from about 400 to 700 billionths of a meter = visible spectrum.  Anatomy of the eye  Cornea  a clear covering that protects the eye and begins to focus the incoming light.  Pupil  a small opening in the centre of the eye.  Iris  the coloured part of the eye that controls the size of the pupil by constricting or dilating in response to light intensity.  When we enter a dark movie theatre on a sunny day, muscles in the iris open the pupil and allow more light to enter.  Lens  a structure that focuses the incoming light on the retina  Retina  the layer of tissue at the back of the eye that contains photoreceptor cells.  How we see  Visual accommodation  the process of changing the curvature of the lens to keep the light entering the eye focused on the retina.  Accommodation isn’t perfect  Nearsighted  focus is in front of the retina  Farsighted  focus is behind the retina  Seeing  Rods  visual neurons that specialize in detecting black, white, and gray colours.  about 120 million rods in each eye  highly sensitive to shorter-waved (darker) and weak light to help us see in dim light  Cones  visual neurons that are specialized in detecting fine detail and colours.  5 million or so cones in each eye  help us to see in colour, but they operate best in bright light.  located primarily in and around the fovea (foe-V-uh) the central point of the retina.  Focus on her eyes  How happy?  Focus on her lips  How happy?  Our peripheral vision (the rods) picks up the low detail brush strokes better so when you see her smile in the periphery, those areas are picked up better  Perception  Perception  created in part through the simultaneous action of thousands of feature detector neurons  specialized neurons, located in the visual cortex, that respond to the strength, angles, shapes, edges, and movements of a visual stimulus  Feature detector neurons work together, so when they see something (like a red box)  Horizontal line feature detectors activate  Red colour feature detectors activate  Square shape feature detectors activate  Then go to the visual cortex  Other neurons compare info with memories  And many neurons firing together create single image  Perceiving colour  We can discriminate among 7 million colour variations  But all based off 3 primary colours:  red, green, and blue  Hue share of a colour conveyed by the wavelength of the light that enters the eye  Shorter = more blue  Longer = more red  Amplitude  or height of the wave for brightness  Bigger or higher perceived as brighter  Perceiving form  Gestalt principles  the whole is greater than the sum of its parts 1. Figure and ground  we structure input so we always have a figure against a ground (image vs background) 2. Similarity  similar stimuli get grouped together 3. Proximity  we group nearby figures together 4. Continuity  we perceive stimuli in continuous ways more than discontinuous ways (lines take smoothest path) 5. Closure  we fill in gaps to complete an image  Perceiving motion  Brain detects motion partly from the changing size of an image on the retina and the relative brightness of objects  Bigger objects are usually closer  Beta effect  the perception of motion that occurs when different images are presented next to each other in succession  The visual cortex fills in the missing part of the motion and we see the object moving.  Phi phenomenon  perceive a sensation of motion caused by the appearance and disappearance of objects that are near each other  Both are examples of the importance of gestalt  Perceiving depth  Depth perception  the ability to perceive three- dimensional space and to accurately judge distance  Both innate and learned  younginfants have a fear of heights but also babies get better hand-eye coordination so learned  Depth cues  messages from our bodies and the external environment that supply us with information about space and distance  Binocular depth cues  created by retinal image disparity (the space between our eyes) and which require the coordination of both eyes  Monocular depth cues  help us perceive depth using only one eye Perceiving depth binocular continued  Convergence  the inward turning of our eyes that is required to focus on objects that are less than about 50 feet away  The visual cortex uses the size of the convergence angle between the eyes to judge the object’s distance.  Accommodation to help determine depth  As the lens changes its curvature to focus on distant or close objects, information relayed from the muscles attached to the lens helps us determine an object’s distance.  Only effective at short viewing distances (threading a needle)  The ear  Take a minute  write down the quietest sounds you can hear in this classroom  Hearing begins with transduction   sound waves are collected by the ear and converted into neural impulses   neural impulses are sent to the brain   integrated into experience   interpreted as sound we experience  Ear is sensitive and can detect very small variations in sound  Ear is particularly sensitive to human voice  Can pick out our children’s voices in a crowd  Quickly recognize a caller  Waves similar to the eye  Similar to the eye, ear picks up sound waves  Vibrating objects cause air molecules to bump into each other  But sound waves are carried within media (air, water, metal)  the pressure changes in the media that the ear detects  Wavelength  (frequency) the number of waves that arrive per second and determines our perception of pitch  Pitch  the perceived frequency of a sound  Longer waves  lower frequency/lower pitch  Shorter waves  higher frequency/higher pitch  Amplitude  height of the sound wave = how much energy it has (how loud)  Larger waves  louder (measured in decibels) frequency  Decibels  Decibel  unit of relative loudness  0 = absolute threshold for human hearing (meaning below that we can’t hear)  Each increase in 10 decibels is a tenfold increase in loudness  20 decibels  leaves rustling (faint)  60 decibels  normal conversation (moderate)  80 decibels  alarm clocks (loud)  Anything over 85 decibels for extended periods can cause permanent hearing damage  130 decibels  ambulances (painful and dangerous)  Ear anatomy  Pinna  external visible part of the ear (funnels sound in and to the auditory canal)  Eardrum (tympanic membrane) at the end of canal  highly sensitive membrane that vibrates with waves  Those vibrations relayed into the middle ear  Ossicles  Ossicles  3 tiny bones (hammer, anvil, and stirrup) Ear anatomy continued  Through middle ear to the cochlea  snail shaped liquid filled tube in the inner ear that contains the cilia  Vibrations cause the oval window  membrane covering the opening to the cochlea to vibrate and disturb the fluid inside the cochlea  Cilia  bundles of fibres that move due to the cochlea that triggers Oval window nerve impulses to go to the auditory nerve then the auditory cortex  How we detect pitch  Again, Pitch  the perceived frequency of a sound  Longer waves  lower frequency/lower pitch  Shorter waves  higher frequency/higher pitch  Loudness is determined by the number of vibrating hairs  Two different theories on how we detect pitch  Frequency theory of hearing  whatever the pitch of a sound wave, nerve impulses of a corresponding frequency will be sent to the auditory nerve  A tone measuring 600 hertz will be transduced into 600 nerve impulses a second.  This theory has a problem with high-pitched sounds because the neurons cannot fire fast enough.  To reach the necessary speed, the neurons work together in a sort of volley system in which different neurons fire in sequence, allowing us to detect sounds up to about 4,000 hertz  How we detect pitch continued  The cochlea relays information about the specific area in the cochlea that is most activated by the incoming sound.  Place theory of hearing  different areas of the cochlea respond to different frequencies.  Higher tones excite areas closest to the opening of the cochlea (near the oval window).  Lower tones excite areas near the narrow tip of the cochlea, at the opposite end.  Pitch is therefore determined in part by the area of the cochlea firing the most frequently.  How we detect pitch continued  Ears on either side of the head enables us to benefit from stereophonic, or three- dimensional, hearing.  If a sound occurs on your left side, the left ear will receive the sound slightly sooner than the right ear  the sound it receives will be more intense, allowing us to determine the location of the sound.  When a sound is equidistant from both ears, we have more difficulty pinpointing its location.  Why dogs/people cock their heads when trying to pinpoint a sound, so that the ears receive slightly different signals.  Hearing loss  Conductive hearing loss  caused by physical damage to the ear (such as to the eardrums or ossicles)  reduces the ability of the ear to transfer vibrations from the outer ear to the inner ear.  Sensorineural hearing loss  caused by damage to the cilia or to the auditory nerve, is less common overall but frequently occurs with age  Prolonged exposure to loud sounds will eventually create sensorineural hearing loss as the cilia are damaged by the noise  More younger people have ear damage and hearing loss  Headphones and earbuds can emit 85-110 decibels  Ear buds that rest in your ear canal can boost sound by about 9 decibels (so 119 db  louder than a car horn or concert…in your ear!)  Hearing loss continued  Conductive hearing loss can often be improved through hearing aids that amplify the sound  But they can’t help for sensorineural hearing loss.  If the auditory nerve is still intact, a cochlear implant may be used.  A cochlear implant  a device made up of a series of electrodes that are placed inside the cochlea.  The device stimulates the auditory nerve cells directly.  The latest implants utilize place theory, enabling different spots on the implant to respond to different levels of pitch.  Tasting  Important to allow us to  Enjoy what we eat  Get energy  Know when foods could be harmful (e.g., spoiled milk)  Picky eaters are biologically predisposed to be careful about what they eat  Tasting + sense of smell helps us  Maintain an appetite  Assess potential dangers (gas leak)  Avoid poisonous food (often linked to bitter)  Tasting  Taste buds  designed to sense chemicals in the mouth  As chew food, it dissolved and enters the taste buds, triggering nerve impulses that are then transmitted to the brain  2,000-10,000 taste buds  Each bud contains 50-100 taste receptors  Activated very quickly  Only live for about 5 days, then new ones are created to replace them  With age, taste buds don’t replace as quickly  Sensory cortex for taste is very close to that for smell, and that explains why so closely linked  Smelling  Cinnamon  What do you think of?  Fish  What do you think of?  Why do smells trigger memories?  They are directly linked to the limbic system (including the amygdala and hippocampus), which are related to emotion and memory  Smells can trigger the strongest memories for people  Olfactory  As we breathe in, we inhale airborne chemical molecules  10 -20 million receptor cells in the olfactory membrane of the upper nasal passage  Olfactory receptor cells have receptor proteins  When an odour receptor is stimulated, the membrane sends neural message up the olfactory nerve to the brain  1,000 types of odour receptor cells  Can detect 10,000 different odours  The receptors come in many different shapes and respond selectively. Like a lock and key,  different chemical molecules fit into different receptor cells, and odours are detected according to their influence on a combination of receptor cells.  Sense of smell peaks in early adulthood and slowly declines by 60- 70 really diminished  Touch  Touch is crucial for development  Infants need tough to thrive (Rhesus monkeys)  Touch communicates warmth, caring, support, and part of social interactions with close others  Skin is the largest organ in the body  Thousands of nerve endings in the skin respond to four basic sensations:  Pressure (only one with specialized receptors)  Hot  Cold  Pain  Sensations  Other sensations are created by a combination of the other four. For instance:  Tickle  stimulation of neighbouring pressure receptors.  Heat  stimulation of hot and cold receptors.  Itching  repeated stimulation of pain receptors.  Wetness  repeated stimulation of cold and pressure receptors.  Other purposes of touch  Proprioception  the ability to sense the position and movement of our body  specialized neurons located in the skin, joints, bones, ears, and tendons  send messages about the compression and the contraction of muscles throughout the body  Without this feedback, we would not be able to play sports, walk, or even stand upright.  Vestibular system  keeps track of where the body is moving  a set of liquid-filled areas in the inner ear monitors the head’s position and movement, maintaining balance.  includes semicircular canals sense rotational movements  and the vestibular sacs connect the canals with the cochlea  sacs sense linear accelerations  vestibular system sends signals to the neural structures that control eye movement and to the muscles that keep the body upright. How do we feel pain When we have a pain, a message gets sent from the sore area to our brain Gets sent SO FAST, to keep us safe and prevent damage or injury For example, if you ever touched a hot kettle, what happened? You probably pulled your hand away really quickly!! Did you have to think about it? NO! Your neurons did it fast to stop you from burning your skin 1. The pain (whichever type) will affect the injured area of your body (head, finger, foot, etc.) 2. The pain receptors in that area will wake up (“activate”) and send a signal from the area towards the brain 3. The brain will then receive that message and send a reply, telling the receptors what to do (“action”) 4. The receptors carry the message back to the injured area 5. Your body will carry out the action, e.g., pull your hand away from the hot kettle  Pain theory  Gate control theory of pain  pain is determined by the operation of two types of nerve fibres in the spinal cord.  One set of smaller nerve fibres carries pain from the body to the brain,  A second set of larger fibres is designed to stop or start (as a gate would) the flow of pain  Why massaging an area where you feel pain may help alleviate it  the massage activates the large nerve fibres that block the pain signals of the small nerve fibres Pain perception Pain is also about perception.  We feel pain less when we are busy focusing on a challenging activity  why athletes may feel their injuries only after the game.  We also feel less pain when we are distracted by humour  Pain is soothed by the brain’s release of endorphins  Endorphins  euphoria after running a marathon  Perceptual system  Sensory interaction  the working together of different senses to create experience.  Examples:  taste, smell, and texture combine to create the flavour we experience in food.  when we enjoy a movie because of the way the images and the music work together.  synesthesia  an experience in which one sensation (e.g., hearing a sound) creates experiences in another (e.g., vision)  selective attention  the ability to focus on some sensory inputs while tuning out others.  Crucial factor in eyewitness testimony  Selective attention  The "cocktail party" effect has been demonstrated many times under controlled experimental conditions. brain's ability to focus one's auditory attention (an effect of selective attention in the brain) on a particular stimulus while filtering out a range of other stimuli, as when a partygoer can focus on a single conversation in a noisy room.  Shows we can limit what we process but…still do unconscious monitoring around us  Perception continued  Sensory adaptation  a decreased sensitivity to a stimulus after prolonged and constant exposure  Don’t smell your house until you leave for a few days and come back  This helps us by saving resources of our mind  it doesn’t need to focus on everything in the environment, just what changes  Anyone ever driven home and not really remember the drive?  Our senses need to make sense of the world, so they need to perceive the same object in the same way  Perceptual constancy  The ability to perceive a stimulus as constant despite changes in sensation is known  Door is closed = rectangle, but when it’s open, we see the edge as a line, but we don’t perceive the door as changing shapes  Cognitive Bias/Interference Stroop (colours and words) + Navon (small letters creating a big letter) What they do: show that our embedded knowledge about our environment impacts how we interact with it. How they cause cognitive bias/interference: because reading or recognizing the big letter is a simpler and more automatic, and that a conflict between the two will increase the time needed for correct processing. What we can use these for: to assess a person’s cognitive processing speed, attentional capacity, and level of cognitive control (executive function).  Illusions  Mueller-Lyer illusion  likely due to the failure of monocular depth cues  Moon illusion  the moon is perceived to be about 50% larger when it is near the horizon than when it is seen overhead, despite the fact that in both cases the moon is the same size and casts the same size retinal image.  The monocular depth cues of position and aerial perspective  Perception and cognition are linked Fundamental Attribution Error the tendency for people to over-emphasise dispositional, or personality- based explanations for behaviours observed in others while under- emphasising situational explanations  Actor-observer Bias a tendency to attribute one's own actions to external causes while attributing other people's behaviors to internal causes Just-world Hypothesis The just-world phenomenon is the tendency to believe that the world is just and that people get what they deserve. Because people want to believe that the world is fair, they will look for ways to explain or rationalize away injustice. 28 The Availability Heuristic A mental shortcut that relies on immediate examples that come to a given person's mind when evaluating a specific topic, concept, method, or decision. 29  The Availability Heuristic  Participants to identify and describe either 6 or 12 occasions in which they were either assertive or unassertive. 7 Six examples  After participants asked to Twelve examples rate own (in)assertiveness. 6.5  Those who recalled six 6 occasions = more assertive  Those who recalled 12 5.5 occasions = more unassertive  Why? It is easier to recall 6 5 events than 12 events Assertive Acts Unassertive Acts Representativeness Heuristic  assessing similarity of objects and organizing them based around the category prototype (e.g., like goes with like, and causes and effects should resemble each other). 33  Then why the shortcuts?  We need to conserve energy.  From evolutionary perspective, it is in our benefit to make quick decisions.  However, we should avoid such intuition when we care about our decisions.  Decision Fatigue  When do you go food shopping? 34  Expectation and perception  Our emotions, mindset, expectations, and context (social norms, cultural outlooks/perspectives) can all influence our perceptions.  If I tell you this lecture is gong to be the best lecture ever…  If I tell you this lecture is going to be the worst lecture ever…  Ourcognition influences our perceptions and our interpretations as well  Placebo Effect a phenomenon in which some people experience a benefit after the administration of an inactive substance or some other effect from something ineffective How do we organize knowledge about out social world?  We use mental representations or cognitive structures that represent knowledge about a concept or type of stimulus, including its attributes, and the relations among these attributes Schemas Mental structures people use to organize their knowledge about the social world around themes or subjects and that influence the information people notice, think about, and remember.40  Schemas  Set of intercorrelated cognitions  Thoughts, feelings, beliefs  When activated allows us make sense of a person, a place, a situation, an event on the basis of limited information.  They help us fill in the gaps!  For example:  Café – Baguette – Boulevard Or  Pizza – Canal – Gondolas 41  The term schema encompasses our knowledge about many things: Other people, Social roles, Ourselves, Specific events.  In each case, our schemas contain our basic knowledge and impressions that we use to organize what we know about the social world and interpret new situations.  Our perceptions shape all of this! 43 Person Schema Cancer Doping Cyclist Tour de Livestrong Cheat France Hero Liar Champion Inspiration Deceit Nike Generous Oprah 44 Role Schema  Knowledge structures about particular role occupants.  Get undressed 45  Scripts  These are schemas about events, and how people behave under certain circumstances:  Relate events, or sequences of events pertaining to specific situations.  They indicate what is expected to happen in a specific situation.  What do you expect when you go out for a dinner date? 46 How heuristics, schemas, and scripts influence perception  Schemas affect everything we perceive and help us interact with the world around us efficiently.  Think and learn new information quickly, with minimal cognitive effort  Categorize and organize new information from existing schemas.  A person looks for social cues consistent with their schema  Scripts of expected behaviors in particular situations influence the impression of a person regarding another person.  Overall?  We often see what we expect to see  Perceptions alter what we focus on  What we see/experience is influenced by our previous perceptions  Anger  - Eyebrows lowered and pulled together  - Lips narrowed  - Eyes wide open, though lowered eyebrows  - Sometimes: mouth open with narrowed lips  Disgust Nose wrinkled Upper lip raised Eyes narrowed in contrast to ANGER Contempt Corner of mouth raised on only one side Like: smiling on one side Sometimes: one side of mouth raised, lips slightly open Happiness Wrinkles in corner of eyes Cheeks slightly raised Corners of lips pulled back eyes Sadness Inner eyebrows raised Upper lids slightly lowered Corners of lips slightly lowered Sometimes: chin 'crumpled'  Fear Inner eyebrows raised and pulled together Raised upper eyelids Tensed lower eyelids Lips slightly stretched horizontally  Surprise Brows raised Upper lids raised Sometimes: mouth opened Universal emotions - Ekman  These emotional responses have evolved as a means of communication and survival  They allow us to quickly convey feelings and react to the environment and social interactions  Emotion determines how we perceive our world, organize our memory, and make important decisions