Memory, Perception, and Visual Processing: Key Concepts and Studies

Who did the study in the first lecture?

Herman Ebbinghaus, early experimental memory researcher

What was studied in the study in the first lecture?

Effect of repetition during initial learning on later memory. Ebbinghaus used lists of items (historically nonsense syllables) and measured how learning on Day 1 affected relearning after a delay.

What are the main findings of the study from the first lecture?

More repetitions on Day 1 → less time needed to relearn after 24h. There was strong evidence that repetition strengthens memory and that successful learning requires optimization of all 3 stages: acquisitions, retention, retrieval

What are the 3 stages of successful learning optimization from the first study?

Acquisitions, retention, retrieval.

What occurs during the acquisition stage in the 3 stages of successful learning optimization?

New information is initially encoded through focused attention and active engagement, forming a preliminary memory trace that is still fragile and unstable

What occurs during the retention stage in the 3 stages of successful learning optimization?

Newly acquired information is maintained and stabilized over time, primarily through consolidation processes, making the memory more durable and resistant to forgetting.

What occurs during the retrieval stage in the 3 stages of successful learning?

Stored information is accessed and brought back into working memory, which strengthens and stabilizes memory traces through retrieval practice

Why does the study from the first lecture matter?

The study shows memory is not all-or-nothing and even when info seems "forgotten," it leaves a residual trace.

What was the conclusion of the first study from the first lecture?

Repetition during acquisition improves later retention, even after forgetting has occurred.

Q: What is repeated retrieval?

the process of actively recalling information from memory multiple times

How does repeated retrieval work?

Repeated retrieval works through active reconstruction of memory. Retrieving info requires reactivating and reassembling distributed neural networks.

Why does repeated retrieval improve learning?

Repeated retrieval improves learning by interrupting and flattening the forgetting curve, keeping memories active over time. It reveals gaps and misconceptions, strengthens conceptual understanding and transfer to new contexts, and increases cue flexibility, making memories retrievable from multiple starting points.

What is Blocking?

A study strat where you practice one topic or skill repeated before moving on to the next

What is blocking's structure?

Topic A → Topic A → Topic A → then Topic B → Topic B → Topic B

What is interleaving?

Mixing different but related topics or problems types within the same study session.

What is interleaving's structure?

Topic A → Topic B → Topic C → Topic A → Topic B → Topic C → Topic B

What is the difference between blocking v interleaving?

Blocking improves short-term performance by studying the same topic repeatedly before moving onto the next, whereas interleaving improves long-term learning and transfer by switching between related topics/problems with the same study session.

What term is used to determine a finding that generalizes in a lab in the real world?

External validity is how applicable the study's findings are to the real world, and applied cognitive research is the application/research that focuses on understanding cognition in the real world (i.e., eye witness memory, driving)

What is functional specialization?

Different regions have some functional specificity

What region of the brain is specialized for the function of vision

V1 (basic features → edges, orientation); Area V4 (colour processing); Area MT/V5 (motion perception)

What region of the brain is specialized for the function of faces

Fusiform face area (FFA → face recognition)

What region of the brain is specialized for the function of voluntary movement

M1 (initiation and control of voluntary movement) in precentral gyrus, frontal lobe

What region of the brain is specialized for the function of sensation

S1 (touch, pain, temp, proprioception) in postcentral gyrus, parietal lobe

How do we know functional specialization exist?

Lesion studies (specific brain damage, specific cognitive deficits), Neuroimaging (fMRI, PET - different tasks activate different brain regions), single cell recordings (some neurons respond selectively)

What is the key assumption underlying lesion studies?

That if damage to region X impairs function Y, then region X is necessary for function Y.

Why are MRIs an useful imaging technique

MRI is useful because it provides high-resolution, non-invasive images of brains structure without exposing individual to ionizing radiation

The EEG provides an estimate of brain activity by measuring what?

EGG measures voltage fluctuations at the scalp caused by synchronized postsynaptic activity of cortical neurons, especially the voltage changes relative to reference electrode

What is perceptual organization?

The process by which the brain organizes raw sensory input into meaningful, structured percepts (objects, patterns, and scenes) rather than disconnected bits of sensation

 What is the goal of perceptual organization?

Transform raw sensory into a coherent, meaningful representation of objects and scenes so that we can recognize them and act on them effectively

Visual illusions often occur because ____?

Vision is inferential, not a direct recording of reality. The brain uses prior experience, context, expectations, and perceptual shortcuts (heuristics → rules of thumb) to interpret sensory input quickly and efficiently, which can sometimes bias perception and lead to illusions

What are the Gestalt principles?

They are a set of rules describe how the visual system organizes elements into coherent wholes, based on the idea that the whole is perceived as more than the sum of its parts (Similarity, proximity, good continuation, closure, simplicity)

How does the Gestalt principles have an effect on perception 

A: 

Similarity → elements that share colour, shape, or orientation are grouped, pattern recognition

Proximity → elements close together perceived as a group, distance signals separation

Good continuation → prefer smooth, continuous lines over abrupt changes, intersecting lines seen as continuous paths

Closure → fill in missing info, incomplete shapes are perceived as whole

Simplicity → tend to interpret a form in simplest way possible

What is top-down processing?

Use prior knowledge/info/expectations to fill in gaps in perceptions

What is bottom-down processing?

Taking in sensory info and constructing representation of what actually is there

What is the difference between top-down and bottom-down processing?

Bottom-up processing is driven by incoming sensory information and builds perception from basic features to whole objects, whereas top-down processing is guided by prior knowledge, expectation, and context that influence how sensory input is interpreted.

What is a post-stimulus mask?

A post-stimulus mask is a visual pattern presented immediately after a target stimulus (e.g., letter, word, or image).

What is a post-stimulus mask used for?

Used to interrupt or limit further processing of a visual stimulus by presenting another stimulus immediately afterward, preventing continued visual processing and isolating early perceptual processing.

What stage does a post stimulus mask primarily affect?

Early visual processing and iconic memory before information reaches conscious awareness.

How does stimulus-onset asynchrony affect post-stimulus masking?

Shorter SOAs produce stronger post-stimulus masking because the mask interrupts ongoing visual processing before the target reaches conscious awareness.

What does post-stimulus masking reveal about perception

Perception is time-dependent and constructed, non instantaneous.

What is stimulus-onset asynchrony (SOA)?

time interval between the onset of the target and the onset of the mask

Why is post-stimulus masking effective even though the stimulus is already gone?

Because visual processing continues after stimulus offset via neural persistence

What does post-stimulus masking show about conscious awareness?

Conscious awareness requires uninterrupted processing, not just a stimulus presentation

Why do researchers use post-stimulus masking in experiments?

to study the timing of perception and dissociate sensory processing from conscious awareness

Gill has a lesion in her left primary visual cortex, which tasks would she struggle with the most?

Gill would have most difficulty with tasks that require detecting or discriminating visual stimuli in the right visual field (i.e., detecting flashes of light, or simple shapes; judging orientation or contrast; reading or recognizing objects; localizing stimuli)

V1 normally processes low-level visual features (edges, orientation, contrast, spatial location) and acts as the gateway for conscious visual perception

What is the dorsal stream?

The "where" pathway processes relevant spatial information for the purpose of guiding action

How does the dorsal stream operate?

The dorsal stream operates by processing where objects are and how to act on them (vision for action), transforming visual input into real-time guidance for movement

What is the Dorsal stream pathway?

Retina → V1 → parietal lobe

Dorsal stream processes?

spatial location, motion, depth, object size and orientation relative to the body

Dorsal stream outputs?

guides reaching, grasping, eye movements, and navigation, continuously describes it

Is the dorsal stream vulnerable to visual illusions, or does it reflect physical reality?

the dorsal stream is less vulnerable to visual illusion than the ventral stream because it is specialized for guiding real-time actions based on physical properties of objects, but it is not completely immune, under certain conditions, illusions can still influence dorsal processing

What disorder is characterized by difficulty seeing motion?

akinetopsia

What is akinetopsia?

A rare neurological disorder characterized by a selective inability, other aspects of vision remain intact (object recognition, colour perception, form, and spatial detail)

What is visual agnosia?

a disorder in which a person can't identify or recognize common visual objects → results from damage to structures within the ventral stream

What is the ventral stream?

The "what" pathway of visual processing that is responsible for object identification

What is associative agnosia?

Can draw, but can't name an object

What is apperceptive agnosia?

can't draw/replicate → perception of features is flawed not knowledge of object, can name objects

What is the difference between associative agnosia and apperceptive agnosia?

Apperceptive agnosia is a deficit in early perceptual processing, where individuals can't accurately form or match visual representations of objects, whereas associative agnosia involves intact perception but an inability to link visual representations to stored semantic knowledge, preventing object recognition

What does it mean to be a split brain patient?

A person whose corpus callosum has been served, preventing communication between the left and right cerebral hemispheres.

Why is the corpus callosum cut in split-brain patients?

to reduce the spread of severe, treatment resistant epilepsy.

What is the primary function of the corpus callosum?

To allow information transfer between the left and right hemispheres.

Why can split-brain patients verbally report stimuli shown to the right visual field?

Because the left hemisphere typically contains language production areas

Why can split brain patients not verbally report stimuli shown to the left visual field?

Because the right hemisphere lacks direct access to speech production

Julie has sustained damage to the ventral stream, she will have difficulty with which tasks?

Julie can't identify objects, could figure out where they are → couldn't put objects in their place

What is early selection?

Idea that attention filters information at an early stage of processing, based on physical characteristics (e.g., location, pitch, loudness), before meaning is analyzed

What is late selection?

Idea that all stimuli are processed for meaning, and attention determines which information reaches conscious awareness or response after semantic processing.

What is the difference between early selection v late selection

Early and late selection differ when attention filters information during processing. Early selection proposes that stimuli are filtered before semantic (meaning) processing, based on physically features like location or pitch. Late selection proposes that stimuli are processed for meaning, and selection occurs afterward, determining which information reaches awareness or guides behaviour

What is controlled processing?

a process that requires conscious use of attention resources → allows for purposeful, goaled directed behaviour

What is automatic processing?

a process that doesn't require attention for its execution

 How does automatic processes contrast to control processes?

Automatic processes occur quickly, unconsciously, and without intentional control, requiring little to no attentional resources and often happening in parallel. In contrast, controlled processes are slow, effortful, and deliberate, require focused attention, and are typically limited in capacity and easily disrupted by multitasking

What is a mental set?

A preparatory mental state that "tunes" cognitive processing to achieve a particular goal

What is task switching?

The ability to shift attention and cognitive control between different tasks or rules

What is the connection between task switching and mental sets?

When task-switching occurs, the brain must disengage from the previous mental set and activate a new one, which requires cognitive effort. This is why people often show switch costs (slower reaction times and errors) when changing tasks, reflecting the difficulty of overcoming the prior mental set.

What is the central processing bottleneck?

It is the limitation in cognitive processing where only one task can undergo central decision-making or response selection at a time.

What is the result of the central processing bottleneck?

When two tasks require central processing simultaneously, one task must wait, leading to delayed reaction times. This bottleneck explains why people struggle with multitasking, especially when tasks require conscious decision-making, even if sensory input and motor responses can occur in parallel.

Where does the central processing bottleneck come from?

It comes from limitations in central cognitive stages of processing, particularly response selection and decision making rather than sensory input or motor execution

How is the central processing bottleneck identified?

It is identified through dual-task experiments → psychological refractory period PRP

What is vigilance decrement

Drop in detection accuracy and respond speed during prolonged monitoring

What is resource depletion?

Declined attention as the result of limited attentional resources becoming exhausted over

What is an underload view?

Vigilance declines because tasks are too easy or monotonous, causing disengagement and win-wandering rather than fatigue.

What is the connection between vigilance decrement, resource depletion, and underload view?

They are competing explanations for why sustained attention declines over time.

What is an exogenous viewing paradigm

Attention task used to study stimulus-drive (bottom-up) attention. Attention is automatically captured by an external cue (e.g., sudden flash or peripheral onset), regardless of the observer's goals or expectations. The cue is typically non-informative, yet it briefly speeds responses to targets appearing at the cued location, demonstrating exogenous attention capture.

What is selective attention?

The ability to focus cognitive resources on relevant info while ignoring competing or irrelevant stimuli in the environment

 What are some tasks used to study selective attention

Dichotic listening task, visual search tasks, stroop task, flanker task, Posner cueing task, Shadowing task

What are the search tasks?

search for a target among distractors (e.g., feature v conjunction search)

What are the stroop tasks?

Requires naming ink colour while ignoring word meaning, testing attentional control and interference

What are the flanker tasks?

Measures how irrelevant surrounding stimuli interfere with target processing

What are the Posner cueing tasks?

Examines how attention is oriented to locations using valid, invalid, or neutral cues

What are the shadowing tasks?

Participants repeated attended information aloud while ignoring unattended input.

What are the costs of task switching?

performance declines - occurs when switching from one task to another (slower rxn times, increased error rates, greater mental effort and fatigue, interference from the previous mental set, time needed to reconfigure task and rules and goals?

When does task-switching occur?

Happens immediately after a switch; when the previous mental set is still active causing interference; when tasks use different rules, responses, or stimulus dimensions; when there is little prep time between tasks; when tasks require controlled processing rather than automatic processing

Why does task-switching occur?

because the cognitive system has to do extra work when changing tasks → previous mental set persists, creating interference that may be inhibited; the brain must reconfigure tasks rules, goals, and response mappings, which take time; cognitive control resources are limited, so switching competes for these resources; response selection is slower when multiple task reps are active

What happens during task switching?

activated; response mappings are updated (slows decision-making); central processing resources are engaged (creating brief bottleneck)

What is Logan's instance theory of automatization (1988)

Explains how tasks become automatic with practice → proposed performance shifts from algorithm-based processing to memory based processing. With enough practice, responding becomes faster, automatic, and less effortful because the brain relies on memory retrieval rather than active computation.

What is memory based processing?

People retrieve stored "instances" of prior task solutions directly from memory

Where does automaticity come from?

Every time you perform a task, the brain stores a memory trace (instance) linking the stimulus to the response. With the repeated practice these instances accumulate, and performance shifts from slow, controlled, algorithmic processing to fast, automatic retrieval of the correct response from memory

What is visual search?

A process of scanning the visual environment to find a target item among distracts, how hard this depends on what distinguishes the target from the distractors.

What is feature search?

target differs from distracts by 1 basic visual feature (i.e., colour, or orientation, or motions). The detection is fast and efficient, with the reaction time is largely independent of number of distractors

What is pop-out visual search?

special case of feature search, target automatically stands out and seems to "jump out" at you. It takes little to no focus attention

What is conjunction search?

Target is defined by a combination of features. Requires focus, serial attention as reaction time is increased as more distractions are added