Cognitive Psychology - Exam 2 - Key terms and Concepts

Perception (definition)

The cognitive function of processing, experiencing, and responding to the information that is provided by the senses.

Sensors/sensory organs

Eyes (vision), nose (olfaction/smell), skin (touch/pressure), tongue (taste), ears (hearing)

What is the sensor’s responsibility?

The sensor converts what physical signal the sensory organ picks up from the environment into an electrical signal/nerve impulse.

Physical signals by sense

Vision = light

Audition (hearing) = sound (vibrations in the air)

Olfaction (small)= chemicals in the air

Touch = pressure on skin

Conversion of physical signals to nerve impulse - Seeing

1) Light comes in through the pupil and hits the retinal photoreceptors

2) Photoreceptors inside the membrane have large protein molecules that change shape when hit by light

3) Changed shape influence flow/ability of ions to pass through the photoreceptor membrane

4) Membrane potential changes, starting electrical signal

Anatomy of the eye

Eye

Pupil - light enters through

Retina - layer of cells (photoreceptors) lining back surface of eye

Conversion of phsyical signal to nerve impulse - Hearing

1) Vibrations (pressure waves) from the reach the ear

2) The pressure wave hits the eardrum and the membrane vibrates with it

3) The eardrum vibrates and the three small bones (malleus, incus, and stapes) vibrate with it

4) The small bones vibrate and the oval window (a membrane) vibrates with it

5) The oval window vibrates and the fluid inside the cochlea vibrates

6) The fluid inside the cochlea vibrates and the basically membrane vibrates

7) Hair cells/mechanoreceptors on the basilar membrane move

8) Changes in the membrane allow ions to pass through

Anatomy of the ear

Ear

Eardrum - has membrane

3 small bones - malleus, incus, stapes

Oval Window - membrane, window that forms and opening into the cochlea

Cochlea - hollow spiral structure, filled with fluid, has second membrane basilar membrane

Basilar membrane - hair cells move and conversion occurs

Color perception

1) The retina has 4 types of photoreceptor cells: 3 cones, 1 rod

2) S (short = blue), M (middle = green), L (long = red) cones, colors are wavelengths

3) Each type of cone contains a different protein molecule in their membrane each sensitive to a particular wavelength (color)

4) the mind infers colors from the strength so the wavelengths that we see

5) S cones have strongest signal, L cones have weakest signal

Adaptation

process of changing the response of retinal receptors by fatiguing certain cones, which can result in altered perception

Pitch perception

1) Closer to the oval window the basilar membrane is narrow and stiff so low frequencies resonate better

2) Closer to the cochlea the basilar membrane is wide and flexible so high frequencies resonate better

3) the mind can infer the pitch of an income sound by assessing at which location along the basilar membrane the harp cells are currently producing the strongest signal

4) beginning of basilar - high pitch, end - low

Cochlear implants

An electrical stimulator provides and electrical signal inside the cochlea at the appropriate location along the basilar membrane corresponding to the pitch picked up by the microphone

Topographic organization

The auditory system is organized by pitch

Low pitched on one end and high pitch on the other

Perception of tone/timbre

Different timbre/tones correspond to different combinations of pitches

Timbre is created by the combination of many different waves that create one pattern received by the ear

Perception by assumption

The brain interprets what the signal from the sense is about which requires the brain to make assumptions and fill in missing info from the signal.

Assumption - Filling in the blind spot

• There is a region on the retina where there are no photoreceptor cells that pick up light because a large bundle of nerves passes through there

• This visual gap can cover a persons face 7 ft away, the Brian fills in info by patina in over the gap

Assumption - the rectangles

• retinal info does not specify what the rectangle display actually shows

• The brain makes assumption to fill in the missing info so than it can interpret an inconclusive sensory signal

Perception in terms of top down and bottom up

Perception is the combination of bottom-up signals that come from the senses and top down info which is what the brain assumes from context.

Herman Von Helmholtz

These plausible inference are made unconsciously, automatic process

Unconscious inference

the perceptual process of intrepreting the sensory signal and filling in missing info based on assumptions

Unconscious inference - Misperception

The sensory info is rigged to invite the brain to make wrong assumptions and therefore interpret the sensory info wrong.

Misconception - perceiving things that aren’t there

Multi-stable perception

The sensory info allows the brain to interpret the info in multiple ways, depending which assumptions your brain decides to go with

We perceive one and the same thing in multiple ways

Auditory streaming

An example of multistable perception

Your perception of a sequence of tones automatically groups into distinct patterns

The dress

An example of multistable perception

Color perception is bottom up (cones giving signals of relative strengths) and top down assumptions

Bottom up, perceived color depends on:

1) reflective properties of object (what color it is is what color it reflect better)

Or

2) color (wavelength composition of the light on the object)

When light of a certain wavelength composition reflects off an object into the eye, many combinations of 1 and 2 can be responsible so the mind must make assumptions.

The same retinal cone signal can come from either possibility.

Gestalt Psychologists

A group of psychologists in the early 20th century who catalogued the principles by which the brain organizes the sensory info in order to form perception.

Apparent movement

A situation in where a sect itself does not actually contain movements but when you look at it you experience it as movement

Demonstrates that perception is not passive, it is the act of interpreting sensory info and organizing it

Inspired the Gestalts

Gestalt Principle 1 - Good Continuation

Points that result in a smooth curve when connected that we perceive as belonging together

Gestalt Principle 2 - Simplicity

Stimulus patterns being perceived in such a way that the resulting structure is as simple as possible.

Gestalt Principle 3 - Similarity

Similar things appear to be grouped together, part of a larger single structure.

Gestalt Principle 4 - Closure

When coherent shapes or objects are not complete in the sensory input, they are nevertheless perceived as complete.

Importance of experience

The mind has a lifetimes of experience interacting with the environment, picking up on regularities in world that explains many of our perceptual tendencies

Importance of experience examples

1) kittens

2) structure

3) faces

Perception in terms of recognition and actions

Recognizing - how things appears to us and why they look the way they do

But perception (processing of sensory data) also guides our actions

Where visual processing occurs

Back of Brian, primary visual cortex

Then continues into two different brain regions

What pathway

Recognition of what things are (bottom)

Where pathway

Must know where things are to guide your actions (top)

How do we know the what and where pathways are separate?

Lesion work

Lesion work - Patient D.F

• Brain damage to the what pathway

• Can describe details they see it can’t recognize/identify object

• Poor perception o orientation when asked to report but performs action of mailing well

Lesion study in monkeys

• when what pathway was removed monkeys could no longer identify shapes

• When where pathway was removed monkeys could not tell which shapes were closer together

Attention

The ability to focus on some paper of the sensory input and ignore other parts.

A top-down factor influences how sensory input is processed and perceived

Donald Broadbent - dichotic listening experiment

• Each ear exposed to different recording But asked to focus on one

• Participants could report well on the recoding they were told to focus on

• Led to filter model of attention

Donald Broadbent - Filter model of attention

Conceptualists attention as a filter between input and memory storage/output that only lets through SOME input

Anne Triesman’s view

The main role of attention in sensory processing is not the processing of individual features but helping those features get bound together into objects where those features co-occur.

Her experiment distinguished between things that require attention and thing that are detected preattentively/automatically.

Feature Search vs Conjunction Search, Anne Treisman

Feature search - target can be identified by a single feature, usually found quickly

Conjunction search - target can only be identified by a combination of features, usually takes longer to find

Automatic Processing

Processing of input that we have a lot of experience with is automatic.

Stroop Effect

We easily process hearing our own name

What directs our attention?

Bottom up and top down factors

Bottom up factors

Properties of the sensory input that automatically draw our attention

Transients

Sudden changes or movement

Strongest bottom up factor that draws our attention

Top down factors

Things we can do to willfully direct our attention to certain input

Spatial Attention

You can willfully pay attention to a particular location

Top down factor

Feature based attention

You can willfully pay attention to a certain feature(s)

Tops down factor

Object based attention

Attentions tends to spread across entire objects

Top down attention often leads to preferential processing of an entire region occupied buy an object.

What areas of the brain are important for attention?

The frontal cortex (front of brain)

The parietal cortex (top of the back of the head)

Balint’s Syndrome (lesion patient)

• Patients that have damage to the parietal cortex in both ides of the brain

• Patients can see and recognize objects but cannot single out and object when presented with multiple

• Attentions cannot be flexible allocated to various aspects of a scene

Unilateral neglect (lesion patient)

• results from lesion to the partial cortex, usually on the right side

• Patients can see and recognize but have trouble paying attention to one side of the scene presented, usually the left side

• Unable to shift attention towards the left side of space

Sensory experience and attention

The brain areas important for attention aren’t the same primary brain areas important for processing sensory information

How attentions areas work

Attention areas send top-down signal to areas the process from the senses. Through those signals they change how the areas respond when info enters from the sensory organs.

Memory

Process involved in retaining, retrieving, and using information after the original information is no longer present

Set of cognitive functions

Patient H.M

• temporal lobes on both sides of the brain medically removed

• HM could no longer form new memories of a particular kind of

• Showed that there are multiple types of memory, some were affected wile others weren’t

Patient H.M Mirror Task

• HM asked to learn how to copy objects in a mirror

• He could look at the mirror while drawing but not the paper, improved the more times he did it

• Everyday he said that he had never performed the task but his performance continued to improved which indicates a type of memory sustained

• This memory system draws on different brain areas than the one that was removed

How are memory types distinguished?

• Duration - how long is the memory retained?

• Content - what kind of info is being retained?

Memory systems

• Long term

• sensory/short term/working memory

Long term memory systems

• Declarative (explicit)

• Non declarative (implicit)

Declarative (explicit) memory

• Type of long term memory - episodic and semantic

• Memory that may last for hours/days/years/lifetime

• Conscious recollection: an ability to explicitly recall an event

• Strongly associated with medical temporal lobes, impaired in HM

• Medial temporal cortex and hippocampus

• Memory is stored in the strengths of synaptic connections

Episodic memory

• about a specific personal experience from a specific time and place (episode/event)

• Can relive the memory

Semantic memory

• various kinds of knowledge

• “Knowing”

Patient KC

• relatively intact semantic memory but affected episodic memory

• Spotty recollection of events but good factual knowledge

Semanticization of memories

Theory that suggests that our memories start off as episodic because we lives and encounter situations that we remember. But over time these get semanticized into knowledge.

Non-declarative (implicit) memory

• involves storing info that has been previously acquired, may not even be aware you have it stored in your system

• Does not involve conscious recollection

Sensory memory (short term)

• info from the sense automatically stays in the system for a while before disappearing so that cognitive functions can be performed on the basis of that information

• Durations of seconds or less

• Automatic

• Sensor memory separate for each of the five systems

Working memory (short term)

• explicit, meaning it involves conscious recollection

• Very brief

• Memory of what is going on RIGHT NOW

• Allows you to keep your mind in the CURRENT context

• Frontal cortex/frontal lobe

• Neurons store the working memory by continuing their firing of action potentials

• Crucial for current behavior

Clive Wearing

• Only has conscious recollection of the immediate past, within minutes

• Anything beyond that he doesn’t remember

• Only working memory intact

How are memories constructed?

• Memory is selective

• Memory is shaped by context

• Actively constructed using various sources of info

Memory Experiment

• asked to memorize pictures shown in a column

• Asked to draw the pictures from memory but each group given different labels paired with the drawings

• Labels influenced how they perceived and remembered the drawings

• Shows that memories are shaped by context

Digit span test

• standard way of measuring the capacity of working memory

• Experimenter cites list of digits to participant and participant has to repeat the digits in the same order

• Working memory capacity generally 4 digits, limit usually 5-9 digits

Memory errors - Flash Bulb Memory

• Memories associated with particularly shocking and emotional events

• People report particularly vivid and detailed memories of their circumstances

• Flash = emotional charge

• Seems very accurate to the person but are actually full of errors

Memory errors - Eyewitness reports

• reliance on eyewitness reports needs to be parched with caution because memories contain errors

• The US Dept of justice has published reports about best practices in interrogating suspects and intrepreting their statements

  • Give people to identify one by one and don’t say how many options there are

Frontal Cortex

• action potentials/nerve impulses that encode task relevant info while it is still present and still while it is gone

Delayed response task experiment

• monkeys had to remember something for a short time, action potentials being recorded in their frontal cortex

• Money is shown where the food is, then passes and covers eyes and has to recall where the food was in order to reach for it after

• During the pause the action potentials were encoding the location of the food

Long term explicit memory storage

• stored in the form of the strengths of synaptic connections in brain networks, regardless of firing

• Weak - Pre-synaptic action potentials has little impact on strength of post synaptic action potentials

• Strong - Pre-synaptic neuron has immediate and strong impact on the firing potentials in post-synaptic neuron

• Strength of connections is critical for long term memory usage

Long term explicit memory storage - day at the beach

• Characterize your experience - hearing ocean, feeling water, seeing ships etc all processed in different sensory brain areas

• Long term memory of that day consists of strengthen synaptic connections between those various neurons across the brain that were involved in you beach experience

• When you recall a long term memory you reinstate a pattern of neural firing in that network similar to the pattern of the original experience

• this is possible because of the strengths of the synaptic connections that define and store long term memory

Standard model of long term memory consolidation

• the medial temporal cortex, specifically the hippocampus, helps overtime to strengthen those synaptic connections by repeatedly reactivating the brain network that was involved in the original experience

• This gradually strengthens your synaptic connections in that network over time

Retrograde amnesia

• Difficulty remembering events that happened shortly before the damage occurred because the memories didn’t have enough time to consolidate

Anterograde amnesia

• damage to medial temporal cortex affects ability to form NEW explicit long term memories