PSYC 101 - MIDTERM LECTURE NOTES

Sensation

physical energy being converted into neural signals by sensory organs

• unique for each of the 5 sense

Transduction

process of converting the physical info of an environment into neural signals

• unique for each of the 5 sense

Perception

organization and interpreting stimulus inputs, becoming aware of a sensation

• realism vs. idealism

• the human mind is not like a “camera” - perception can be altered

Top-Down Control

when knowledge of strategies influence basic processing

• using past experiences and learning to solve future problems

• perception of shape constancy is formed via previous experience

  • ex. the door shape changes from different perspectives (open/closed)

  • but you still know it’s a door even when the shape changes

Vision

Light reflected from surfaces translated into information about an object’s shape, colour, and position

Audition (Hearing)

vibrations cause change in air pressure moving through the listener’s ears

Touch

pressure of a surface of the skin to detect shape, texture, temperature

Taste and Smell

molecules dispersed in air and/or saliva to identify a substance

Properties of Light Waves

• wavelength (colour)

• amplitude (brightness)

• purity (saturation)

Saturation

vividness of an object

• intensity of color

Auditory Transduction

• frequency → perception of pitch

• amplitude → perception of loudness

• complexity → perception of timbre

Sensory Adaptation

change in sensitivity of sensory receptors over time

Neural Fatigue

declined sensitivity with prolonged stimultion

• ex. getting used to an itchy sweater the longer you wear it

Dark Adaptation

getting used to low levels of light in a dark room, becoming more sensitive to bright light

• due to the recovery of photoreceptors

Absolute Threshold

minimal intensity to just barely detect stimulus

• detected in 50% of the trials

• required to have complete control of external variables (ex. seeing candlelight 48km away → requires complete background darkness)

Just Noticable Difference (JND)

minimal change in a stimulus that can barely be detected

• ex. hearing your phone ring in a loud club

Weber’s Law

JND increases in proportion to the background intensity

• ex. candle 48km away → changes depending on how dark the background environment is

Signal Detection Theory

2 equations to distinguish perceptual sensitivity from decision criterion

Perceptual Sensitivity

“how good one’s hearing is”

Decision Criterion

bias towards one option

• positive or negative

• yes or no

Positive Response Bias

tendency to say “yes” on most trials

Negative Response Bias

tendency to say “no” on most trials

Fovea

“sweet spot” in the retina”

• contains photoreceptors

• rods (120 million) and cones (6 million)

Iris

muscle controlling the pupil

Retina

“back wall” of the eye

• where transduction takes place

• cells in retina → receptive field that respond to stimuli in a particular part of space

Cornea

“outer case” shell guarding the eye

Pupil

black dot in the centre of the eye

Normal Vision

focus the image on the retina at the back of the eye

• both for near and far objecs

Nearsightedness

seeing clearly what is nearby, but distant objects are blurry

• light from the objects is focused in front of the retina

• laser eye surgery → “shaves away” to regulate how distance is perceived

Farsightedness

distant objects are clear, but objects nearby are blurry

• point of focus falls beyond the surface of the retina

Blind Spots

points of the retina where there are no cell activity

Photoreceptors

rods and cones

Rods

120 million

• fovea has the majority of the cones

• NOT colour focused → more sensitive and used for seeing dimly light objects

Cones

6 million

• less sensitive

• used for colour vision and acuity

Acuity

sharpness of an image

Bipolar and Retinal Ganglion Cells

summarize information from a patch of photoreceptors

• a ‘receptive field’

• fewer cones are summated by a single retinal ganglion cell (superior acuity, ex. spatial resolution)

Trichromatic Theory

• 3 types of cone cells

• balance of firing across 3 cone types yield colours

  • pattern coding

Colour Opponent Theory

some colours work against others

• red/green

• blue/yellow

• black/white

Primary Visual Cortex (VI)

the ‘what’ and ‘where’ streams of the brain

Retinal Ganglion Cells

carry info out of the eye

Sensation vs. Perception

sensation:

• “no sensation for a whale object in one’s blind spot”

perception:

• “filling in missing info”

• ex. a dog where a part of it is in one’s blindspot

  • you don’t see a dog w/a hole in it

Superior Colliculus

• in the tectum

• handles visual orientation

  • ex. turning attention to a flashing light in your blindspot

Optic Chiasm

‘nasal’ fields cross here

Lateral Geniculate Nucleus (LGN)

relay station in the thalamus to the occipital lobe

• set of synapses

• every sense (except smell) has a “central” relay station in the thalamus

Left Visual Field

seen through the right side of each eye

Right Visual Field

seen through the left side of each eye

Contra-lateral Control

how each visual field (left and right) are seen through the opposing side of each eye

Scotoma

• cortical ‘blind spot’

• partial blindness due to damage in the primary visual cortex

Single-Neuron Feature Detectors

area V1 contains neurons that respond to specific orientations of lines, bars, or edges that fall within the cell’s receptive field

• edges/lines represent action potential

• more lines → more interest

• less lines → less interest

Visual Processing from Eye to Cortex

eye → thalamus → primary visual cortex → movement, info from both eyes, orientation and widths of lines, colour → (two options)

• parietal lobe (perception of location and movement)

• temporal lobe → (three-dimensional form perception)

Area V4

• deals with colour

• damage to the area → cerebral achromatopsia

  • parts of the visual field are seen without colour

Area V5

• deals with visual motion

• damage to the area → akinetopsia

  • when movement is seen more like “frame by frame” shots rather than fluid

Ventral Pathway

• temporal lobe

• identifies ‘what’

  • ex. what the object is, its colour

Dorsal Pathway

• parietal lobe

• location and actions related to input

• ‘where’ or ‘how’

• think → “how do I reach/grab the object?”

• movement

Prosopagnosia

inability to recognise (familiar) faces

Agnosia

inability to recognise objects

• but not necessarily forgetting ‘how’ an object is used

Gestalt Laws of Perceptual Organization

“sum of the objects are greater than the 'whole’”

• simplicity

• closure

• continuity

• similarity

• proximity

• common fate

The Spotlight Metaphor

• the brain doesn’t process the entire visual field at once

  • it prioritizes what changes and what feels most important

• attention is like a ‘flashlight’ that you move around your visual field

The Binding Problem

how features are linked together so we see unified objects in our visual world

• rather than free-floating or miscombined features

• attention is the glue that binds individual features into a whole percept

Perceptual Constancy

our perception is stable despite dramatic changes in incoming sensory signals

• cells of an object completely change when you change your fovea (sweet spot) focus

  • ex. “looking down at a notepad when the prof is talking” → prof is still in view, but looks different

Shape Constancy

stable despite differences in visual details or viewing angles

• ex. the door

Colour Constancy

across different lighting conditions

• ex. the viral blue/yellow dress

  • how people interpret lights (ambiguous)

  • has to do with the amount of colour wavelengths

Size Constancy

across different distances

• depth perception

• how we know the size of something

Depth Cues

monocular cues (one eye) and binocular cues (two eyes)

Monocular Cues

pictoral cues and motion parallax

Binocular Cues

convergence and retinal disparity (steropsis)

Pictorial Cues

• interposition

• size

• linear perspective

• texture

• haze

• shading

• elevation

linear perspective

parallel lines intersect at vanishing point in the centre of an image

texture gradient

objects closer (ex. ground texture) are more visible than objects further in the background (ex. the mountains)

Interposition

used to gauge distance and arrangement of objects in a photo

• ex. front/back of an object arrangement

Relative Height (Elevation)

closer objects in a photo look bigger due to perspective

Ponzo Illusion

lines of the same length look shorter/longer due to the background image of the train tracks

The Muller Lyer Illusion

lines of the same length look shorter/longer due to the arrows on the ends

Motion Parallax

• non-pictorial monocular cue

• useful for moving objects

• objects closer than our fixation move in the opposite direction to us

• ex. a train

  • closer objects (close-by trees, tracks) are moving fast while background objects (mountains, skyline) move slower

Convergence

eyes turn inwards for near objects

• think ‘cross eyed’

• mainly used for close-up objects

Binocular Disparity

objects that are closer generate 2 retinal images that are more disparate

Ossicles

bones in the ear to help amplify a pressure wave in air to a pressure wave in fluid

• ex. in a pool → ossicles have to amplify move to hear better in water, or fluid

Cochlea

“snail” shape in the ear where auditory transduction occurs

Auditory Transduction

• occurs in the cochlea (snail)

• different sections of the basilar membrane vibrate to a different pitch frequencies

  • and stimulate hair cells along its length

Tastants

• commonly food molecules

• dissolve in saliva and stimulate the tipes of taste receptor cells

• each taste bud contacts branch of cranial nerve at its base

The 5 Types of Taste Receptors

• salt

• sour

• bitter

• sweet

• umami

Flavour

• F = taste x smell

• glustatory cortex (frontal lobe)

  • passes info directly to olfactory cortex

Pattern Coding

• enables 339 receptors to recognize 10,000 different odours

• humans do not get “memory full” problems from too much info because of this

Touch

• receptors respond to stimulation within receptive fields on the skin

  • pressure, vibration, temperature

• pain receptors → populate all body tissues that feel pain

  • around bones and within muscles and internal organs, and under the skin surface

Sensory Pain

pain felt on a physiological level

• somatosensory cortex

Emotional Pain

pain felt on a physiological level

• ex. social exclusion, empathy of pain, motivation to avoid pain

  • limbic system and prefrontal cortex

Learning

“the aquisition from experience, new knowledge, skills, or responses”

Habituation

becoming used to an external stimulus after prolonged exposure

• ex. the slug’s withdrawal becoming desensitized the more it’s poked

Sensitization

becoming more sensitive to a stimulus over time

• ex. the slug’s withdrawal reflex becoming more extreme the more it is poked

Classical Conditioning

aka: Pavlovian Conditioning

• a neutral stimulus gains significance

• “one thing leads to another”

• learner/animal are more of a witness to the events

Operant Conditioning

aka: Instrumental Conditioning

• shaping an individual’s behaviour

• “how to get the good stuff” mindset

  • or “how to get away from the bad stuff”

• learning how to use a new device

Steps of Classical Conditioning

1. before conditioning

   • food (unconditioned stimulus [US])

   • dog salivation (unconditioned response [UR])

2. before conditioning

   • tuning fork (neutral stimulus)

   • no dog salivation (no response)

3. during conditioning

   • tuning fork (CS) - food (US) = dog salivation (UR)

4. after conditioning

   • tuning fork (CS)

   • dog salivation in expectance of food afterward (CR)

Unconditioned Stimulus

usually provides an unconditioned response via innate knowledge

• ex. having the innate knowledge to be scared of loud noises or salivate at food

Counter-Conditioning

• creating a conditioned response to combat a negative emotion

• usually used to face phobias

Phobias

associated with some kind of classical conditioning

• often developed in childhood → lost in adulthood

BF Skinner’s Principles of Operant (Instrumental) Conditioning

reinforcement and punishment

• positive and negative

Thorndike’s Puzzle Box (Law of Effect)

cat’s “escape room” box

• rewarded actions are ‘stamped in’

• unsuccessful actions are ‘stamped out’

  • after learning how to open the box the first time, the cat solves the problem faster next time in the box

  • ‘learned knowledge’

Positive Reinforcement

• “pursuing pleasure”

• ex: parent giving you a hug for doing your chores

Positive Punishment

• presenting penalties and alarms

Negative Reinforcement

• “avoiding harm”

• increase behaviour to remove unpleasent stimulus

• ex. seatbelt warning sound. drug withdrawal effects by taking more drugs