Sensation and Perception: An Overview

Sensation and Perception

• Distinguish between sensation and perception
• Describe the concepts of absolute threshold and difference threshold
• Discuss the roles attention, motivation, and sensory adaptation play in perception

Retinal Image and Mental Process

• The retinal image helps us perceive distances, with closer objects appearing larger, and farther objects appearing smaller
• The mental process addresses the difference between the visual properties of the retinal image and our visual experience
• This process is more complex than our everyday experience implies

Sensation

• Sensation involves the detection of physical stimuli such as light, sound, and smell

Perception

• Perception is the interpretation of sensations in the brain

Mental Process and Unconscious Inferences

• Our unconscious mind interprets visual information through retinal image
• Our unconscious mind interprets things through eye movement cues
• Binocular convergence (top side of retina) enables depth and distance perception by using both eyes
• Accommodation (bottom side of retina) involves adjusting the eyes to focus

Indirect Perception

• Perception is indirect because our mind first presents an idea of an object and then directs our attention to the object we are looking for

Light and Color Vision

• Light is electromagnetic radiation that creates electrical signals for the mind to perceive sensation
• ROYGBIV represents the colors of the visible spectrum: red, orange, yellow, green, blue, indigo, violet
• The trichromatic theory: color vision states that all colors are produced by combining red, green, and blue light
• The opponent-process theory: color is coded in opponent pairs: black-white, yellow-blue, and red-green

Afterimages

• Afterimages are the continuation of visual sensation after the removal of the stimulus
• Visual processing on the retina uses the trichromatic theory
• After the stimulus, cells respond with the opponent-process theory

Parts of the Eye

• Pupil regulates the amount of light entering the eye
• Lens focuses light rays on the retina through accommodation
• Presbyopia: Presbyopia is an age-related loss of focus on nearby objects
• Retina: The retina, the tissue lining the back of the eye, contains receptors
• Cones: Cones are receptors for bright environments, fine detail, and color vision
• Rods: Rods are receptors for dark environments, blurry vision, and peripheral vision.

Transduction

• Transduction is the conversion of sensory stimulus energy to action potential; rods and cones convert patterns of neurons firing in the brain to interpret what is happening
• Visual neuroscience focuses on how visual features are represented in the brain as well as firing patterns of neurons along the visual pathway

Absolute Threshold

• The absolute threshold is the minimum amount of stimulus energy needed to detect a stimulus 50% of the time

Subliminal Messages

• Subliminal messages occur when stimuli are received below the threshold of conscious awareness
• Symptoms might be present before the body is aware of an issue or diagnosis

Just Noticeable Threshold/Difference Threshold

• The level of intensity determines the ability to detect a stimulus
• The difference threshold detects changes in stimulus intensity, which varies depending on the stimulus intensity itself

Eye Anatomy

• Fovea: small indentation in the back of the eye to focus images perfectly using cones
• Rods: lacks color function, works best in low light for cones
• Cones: work well in bright light
• Optic nerve: cells that exit the back of the eye
• Optic chiasm: a nerve where each eye merges just below the rain

Retinal Ganglion Cells (RGC)

• Retinal Ganglion Cells (RGC) help identify measured firing rates under different conditions
• Ganglion cells respond to enhance contrast when light is shined on the retina
• Edge detection happens as contrast helps with object recognition
• Ganglion cells are the first neurons in the retina to respond with action potentials
• The response of the ganglion cells depend on the cell that feeds the ganglion cell

Receptive Field Subregions

• Areas within the receptive field are divided into a center and a surrounding region
• ON center/ OFF surround cells increase response as flashing small bright light spots in the center subregion increase the action potential
• Sunlight in the eye causes black spots you see in front of you or black screen you see when you move your eye

Primary Visual Cortex

• Neurons respond to the retinal image, electrical signals occur (action potential)

Vision to Brain Pathways

• Dorsal stream ("where" pathway): extends into movement areas of the brain (posterior parietal lobe)
• Damage to the dorsal stream causes optic ataxia, the inability to perceive movement and use vision as a guide
• Ventral stream ("what" pathway): extends into memory areas of the brain (inferior temporal lobe)
• Damage to the ventral stream causes visual agnosia, the inability to recognize objects

Processing Types

• Bottom-up processing: sensory information from a stimulus in the environment that drives a process
• Top-down processing: refers to the use of knowledge and expectancy to drive a process

Sensory Adaptation

• Sensory adaptation is a process of getting used to our senses through a constant environment
• Attention and motivation affect sensory adaptation, as does something that is in our site that will be most preserved
• Motivation can detect a meaningful stimulus shifting our ability to discriminate between a true sensory stimulus and background noise

Inattentional Blindness

• Inattentional blindness is the failure to notice something completely visible because attention is focused on something else

Signal Detection Theory

• Signal detection theory is the ability to identify a stimulus when it is embedded in a distracting background

Amplitude and Wavelength

• Amplitude: the amplitude of a wave is the distance from the center line to the top point of the crest or the bottom point of the trough
• Wavelength: the length of the wave from one peak to the next
• Related to the frequency of the given waveform
• Frequency: refers to the number of waves passing a given point in a given period and is often referred to as Hertz (Hz)

Light Waves

• The visible spectrum is the portion of the larger electromagnetic spectrum
• The human visible spectrum is associated with wavelengths ranging from 380 to 740 nm

Sound Waves

• Physical properties of sound waves are associated with aspects of our perception of sound
• The human audible range is 20-20,000 Hz
• Frequency of sound is associated with our sound's pitch

Sound Terminology

• Pitch: the perception of frequency
• Place theory: Perception of pitch corresponds to the place of vibration along the cochlea
• Frequency theory: Perception of pitch corresponds to the frequency or rate at which hair cells vibrate
• Amplitude: perception of amplitude: low amplitude=quiet, high amplitude=loud
• Timbre: refers to sound's purity, affected by the complex interplay of frequency, amplitude, and timing of sound waves.

Parts of the Ear

• Outer ear: pinna funnels sound waves to the middle ear
• Middle ear: vibration of the eardrum amplified by the three tiny bones (malleus, incus, stapes)
• Inner ear: vibrations converted to a neural signal in the cochlea.
• Cochlea: the fluid-filled coil in the inner ear that contains the receptors for hearing

Age-Related Hearing Problems

• Presbycusis: age-related hearing loss starting with higher frequencies
• It's caused by loss and deterioration of hair cells in the opening of the cochlea
• Hearing problems cause failure to transmit neural signals from the cochlea to the brain causing sensorineural hearing loss which is a disease that results in Meniere disease.
• Meniere disease: ringing/ buzzing in the inner ear and vertigo (spinning in the inner ear) are symptoms
• Hearing aids can not cure these losses
• Congenital deafness: not being able to hear from birth
• Conductive hearing loss: a problem in delivering sound energy to the cochlea
• Hearing aids help with conductive hearing loss

McGurk Effect

• McGurk effect: How different background sounds come together and create hearing
• Audio of one sound paired with video of another makes a third sound perceived

Traditional and Ecological Approaches to Vision

• Traditional approaches create illusions about visions, stemming from imagination in the brain
• Traditional research minimizes movements in the body
• Ecological approaches to hearing focus on stimulation and reality
• Understanding perception requires considering real-world movement as perception unfolds continuously
• Even small moments can correct errors of perception

Static Images

• A series of static images represent seeing the world from a single viewpoint/perspective
• Perception can be direct, according to the ecological approach

Vision Research

• Alhazen: Alhazen did studies on vision and changed the way we see light
• In his experiment to prove light travels in a straight line using a camera obscura
• Kepler: Kepler performed studies on vision and revealed that visions occur through a picture of the visible thing

Affordances

• Affordances: opportunities for action

Consciousness

• Consciousness is the awareness of internal and external events
• Some unresponsive patients have covert consciousness
• Light information is sent from the retina to the suprachiasmatic nucleus in the hypothalamus (biological clock)
• The suprachiasmatic nucleus sends signals to the pineal gland, increasing melatonin production as light decreases
• Melatonin makes you feel sleepy and blue light from smartphones suppresses melatonin

Sleep/Wake Cycle

• Sleep/wake cycle is a circadian rhythm which causes biological activities to rise and fall in an 24-hour cycle (cira- about)
• Biological clock corrects itself with reference to environmental cues but continues to function without them
• Younger adults/ evening people are more alert later and older adults are more alert in the morning

Sleep Deprivation

• Sleep deprivation occurs when you do not get enough sleep
• Sleep deprivation causes you to feel cold
• We need sleep to conserve energy, stay away from predators, and help thinking/function
• Research shows that good sleep improves cognitive ability relating to memory, learning, and problem-solving

Sleep Incubation Activity

• IV: 8-hour incubation activity (sleep, wake-night, wake-day
• DV: the percentage of people in each group gaining insight
• Participants that get sleep are more likely to gain insight because sleep is important to refresh the brain

Sleep Stages

• The brain does not turn off when we go to sleep
• Sleep labs:
• EEG: electro-encephalograph records brain activity
• EMG: electro-myograph records muscle activity
• EOG: electro-oculography records eye movements
• Sleep involves cycling through distinct stages; participatory EEG (electro-encephalograph)

Brain Neurons During Sleep

• Groups of neurons tend to fire at the same rate and the same time, synchronizing metronomes
• EEG is not sensitive enough to detect activity of individual neurons
• Summed activity of neurons is measured by EEG as a brain wave
• Brain waves differ in frequency and are varied in predictable ways
• They pass through 5 stages during sleep distinguish them from awake brain waves
• Stages include: brain waves are awake and alert with higher frequency and small amplitude
• First four stages in the sleep cycle, brain waves get slower frequency and larger amplitude

Stages of Sleep Cycle

• Stage 1: myoclonic jerks (twitching in the legs) and hypnagogic imagery (light patterns in the eye when they are closed)
• Stage 2: sleep spindles occur, heart rate slows, body temperature decreases, eye movement ceases, but you're still sensitive to events
• Stage 3-4: delta wave sleep (slow wave sleep) and is the deepest stage of sleep, needed to feel refreshed in the morning
• Stage 4: resembles state 1 but then the person enters REM sleep
• Brainwaves resemble the waking brain and there is almost no muscle-tension, dreaming occurs
• Sleep cycle repeats about 4-5 times per night, and each cycle is about 90 minutes

Dreaming

• Lucid dreaming: The experience of realizing that you are dreaming
• Lerberge (2000): measured EEG while self-identifying lucid dreaming and estimated that it takes 10 seconds while awake and dreaming

Freud: Dreams as Wishes Fulfillment

• Dreams as wishes fulfillment: what you want in real life, you see it in your dreams
• Manifest content (the dream): what we think about in real life
• Latent content (the hidden meaning of the dream): why we thought of what we did during the day

Activation Synthesis Theory

• Activation synthesis theory is that our brain interprets what it remembers in the day when it is awake, the brain attempts to make sense or construct a story out of random brain activity during REM sleep
• This theory says models process our centered emotions, memory and sensory systems and cause it because we reflect back why we dream because when our brain is awake, what we store is presented when our body falls asleep but our brain tends to get awake again and process those emotions, and thoughts You call it dream interpretation

Cartwright's Theory

• People often dream about problems in their waking life
• Dreams are not logic, they offer a unique and creative place for your waking life problems to process and workout
• Working out solutions to the problems in the brain is called anecdotal evidence
• Memory consolidation means new memories and our day events are replayed in our head by REM sleep

Effects of Sleep Deprivation

• The effects of sleep deprivation is important
• If you don't sleep, you die
• Memory consolidation theory of dreaming is the sleeping that strengthens our memory to stay with our brain and when we wake up, the brain functions better

Psychoactive Drugs

• Psychoactive drugs selectively alter neurotransmitter activity in the brain
• They either block reuptake or mimic neurotransmitters produced internally
• Some opioids mimic the body's own natural painkillers called endorphins
• Alcohol: what it does to our brain and affects our conscious brain
• Blood alcohol content is a sedative and depressant
• Alcohol defeats the central nervous system activity
• Causes slow thinking, impaired concentration, walking, and muscular coordination, and unconsciousness if the level is more than 4

Effects of Alcohol

• Lang et al (1975) found that males who expect that they are drunk are more aggressive
• The effects of psychoactive drugs occur through their interaction with the endogenous neurotransmitter systems
• Stimulants include Cocaine- it increases heart rate, blood pressure, and body temperature
• MDMA(Ecstasy) - high doses can cause brain toxicity and death
• Sedative Hypnotics Depressants include alcohol: it decreases heart rate, blood pressure, motor disturbance, memory, and respiratory function
• A high enough dose can induce sleep and death.
• Opiates include Heroin causes a decrease in pain and gut motility and decreased respiratory function
• Hallucinogens include Marijuana: It increases heart rate and blood pressure that disappears overtime

Learning Defined

• Learning: A change in behaviour or thought through our experience
• Learning does not need to involve facts and does not always need to be useful, if able to you can pick wrong behaviour such as smoking.

Habituation

• Habituation: A reduced response when a stimulus is presented repeatedly
• Experiment can learn whether: plants or can reduce their response because they're exhausted
• Dishabituation: Response occurs when a stimulus is changed or a new stimulus is introduced

Classical Conditioning

• Classical conditioning: An automatic response (not done in purpose) transferred to a neutral stimulus (specific response)
• Unconditioned stimulus (UCS) is a stimulus that evokes automated response (smell of food)
• Unconditioned response (USR): an automatic response to a UCS like drooling

Conditioned Stimuli and Responses

• Conditioned stimulus: an automatic stimulus developed from a repeated unconditioned stimulus
• Conditioned response: when you continue the response based on repeated unconditioned stimulus
• Stimulus generalization: when you respond to a new stimulus in a way similar to the conditioned response generally produced by an established CS
• Responding similarly to the can opener sound and mixer sound
• Stimulus discrimination: Responding differently to various stimuli that are similar: responding differently to the sound of a mixer and can opener
• Phobia: Little Albert demonstrates how irrational fears can develop from classical conditioning

Evaluative Conditioning

• Evaluative conditioning: Your response reflects whether you like or dislike a stimulus based on positive or negative stimuli
• Nature vs. Nurture: Behavior is learned through nurture, and you pick the behavior

Aversion Therapy

• Aversion therapy: Aims to change a behavior into a good one by pairing it with an unpleasant stimulus to decrease a bad behavior
• Modify negative / problematic behavior with parking it with an unpleasant stimulus/ UCS:emetic/ alcohol
• UCR:feeling nauseous :not liking it because of problems

Operant Conditioning

• Operant conditioning has responses that are controlled by their consequences
• Some responses are voluntary
• Some responses are influenced by what follows, so it's polite to say thank you
• Law of effect: knowing the consequences and then acting based on them
• Reinforcer: an event or a behaviour that is either continued or decreased based on the consequences
• Shaping by successive approximations: Reinforce closer and closer approximations of a desired response to use in dogs training and shaping the behavior based on the desired response
• If the dog follows the rule through a kind of behavior, it will be continued and if not a different behavior will be acted - Positive reinforcement: continued behaviour - Negative reinforcement: decreased behaviour to get the desired rule followed

Unconditioned Stimuli

• Positive Punishment: Adding unconditioned stimulus to decrease a behaviour
• Negative punishment: removing a pleasant stimulus to decrease a behaviour
• Operant conditioning chamber
• IVs: type of reinforcement, schedule of reinforcement involves positive punishment, schedule of reinforcement

Schedule of Reinforcement

• Continuous vs. partial reinforcement
• A type of schedule of reinforcement where Continuous reinforcement indicates you'll continue a behaviour in order receiving the same benefit
• After a behaviour is learned/reinforced, researchers turn to partial reinforcement
• There are four schedules of partial reinforcement

Partial Reinforcement Schedules

• Fixed-ratio schedule: Reinforcement after a set number of non-reinforced responses (e.g., reward cards)
• Variable-ratio schedule: Reinforcement after a variable number of non-reinforced responses
• Fixed-interval schedule: Reinforced after a set amount of time
• Variable-interval schedule: Reinforcement after a variable amount of time Ratio schedules produce more rapid responding, whereas fixed schedules (FI) pause after each reinforcement

Types of Reinforcement

• Variables vs. fixed schedule: Variable schedules resist extinction more, are more productive because you never know when reinforcement will arrive, you may have to wait
• Positive reinforcement: tapping on the go train to avoid a ticket
• Positive punishment: Knowing an action causes a negative reaction
• Parking tickets- decreases likelihood of not parking somewhere you are not supposed to
• Negative punishment
• DV: rate of response, resistance to extinction with no longer enforcing the behavior
• Observational learning with mirroring neurons and the ability to imitate
• Cognitive Models of Learning where it has biological and Nurture influences on learning
• There's preparedness with the proposal that humans have an ability for fear of losing

Behaviorism and Conditioning

• Behaviorism: behaviors are learned through nurture
• Behaviors are learned.
• Conditioning happens when there's learning connections between events and behaviour
• Pavlov's experiment with dogs show associating different sounds of foods
• Conditioned responses are not permanent and may fade over time