Perception/Imagery & spatial cognition

distal stimulus

Real world objects and patterns to be perceived

proximal stimulus

The pattern of neural firing that the distal stimulus creates on the sensory organ

bottom-up processing

Processes based upon properties of the proximal stimulus (aka, data-driven processes)

top-down processing

Processes based upon prior knowledge and interpretation of the context (aka, conceptually-driven processes)

constructivism

Our perception of objects and patterns depends on interpreting a sometimes ambiguous proximal stimulus

•Perception involves elaborate stages of processing

•Object recognition requires comparison to stored representations (memories)

direct perception

Direct perception (aka, ecological approach) originated from the work of J. J. Gibson on visual perception

•Premises of Direct Perception

•Light reaching the retina provides unambiguous information about the environment

•No elaborate processing required to interpret the retinal image

•Environmental stimuli have invariant properties

invariance

property of a stimulus that does not change despite rotation of the object, greater distance, changes in lighting etc.

•Gibson believed many invariant properties were conveyed to an observer via movement of the object or the observer

•EX: Biological motion

affordance

a perceived opportunity for action provided by an object

word superiority effect

Letters are easier to recognize if part of a word than if part of a letter jumble (nonword) or presented alone

•An effect of top-down processing

missing letter effect

Letters embedded in function words within sentences are difficult to detect, presumably because less attention is directed to them

geon

Geons, the primitives of object recognition, are identified in the retinal image

•Geons (36 in total) are simple 3-D shapes

visual receptive field

region of visual space within which a particular neuron will respond to stimulation

face patch

an area of cortex responsive mainly to faces

ventral stream

a system of interconnected regions of visual cortex involved in the perception of form, beginning with the striate cortex and ending with the inferior temporal cortex

dorsal stream

a system of interconnected regions of visual cortex involved in the perception of spatial location, beginning with the striate cortex and ending with the posterior parietal cortex

repetition priming

shortening of response time to a stimulus on its second presentation

apperceptive visual agnosia

Difficulty recognizing objects presented visually

•Can see "simple" visual attributes such as lines and colors

•Cannot recognize different views of the same object as being the same

•Cannot copy drawings

associative visual agnosia

Can perceive some aspects of shape

•Difficulty in naming objects presented visually

•Can copy (laboriously) but difficulty naming

optic aphasia

impaired naming of only visually present objects

prosopagnosia

inability to recognize faces

template matching and describe its limitations as an explanation of object recognition

Object is perceived by comparing the proximal stimulus to a template stored in memory

feature analysis models are and explain how do they overcome some of the limitations of template models

This holistic approach proposes that an object is perceived by comparing the proximal stimulus to a template stored in memory

-A small number of features can support recognition of a large number of objects

pandemonium model of letter recognition

Feature demons are each tuned to recognize a particular letter feature

Cognitive demons respond to unique combinations of features

Decision demon decides which letter was presented based upon which cognitive demon shouts the loudest

Pandemonium Model of letter recognition advantages

a small number of features is sufficient to recognize a large number of stimuli

Pandemonium Model of letter recognition disadvantages

Purely bottom-up model; cannot use context to recognize ambiguous input

recognition by components theory

Irving Biederman

•Proposes our visual system recognizes objects by identifying geons in the retinal image and mapping arrangements of geons to object descriptions in memory

how many independent dimensions of facial information are coded by face patch cells according to Chang and Tsao

50

Describe the findings of Vuilleumier et al. with regard to whether object recognition is viewpoint dependent or viewpoint invariant

used repetition priming, mental chronometry, and fMRI imaging to examine the invariance question

Describe prosopagnosia and describe its two forms

Inability to recognize faces

Developmental & acquired

What is Imagery and Spatial Cognition?

Study of how mental imagery relates to memory, cognition, and perception

What is Vividness of Imagery?

Varies among individuals and modalities; inconsistently predicts performance; measured with PSI-Q.

Q: What is the Fundamental Question About Imagery?

How are images stored in memory? Competing theories: Analog representation (spatial-like) vs Propositional representation (abstract, language-like)

Q: What is Shepard’s Mental Rotation Experiment?

Showed that decision times increased with rotational separation, demonstrating that mental rotation resembles physical rotation.

Q: What did Cooper and Shepard demonstrate?

That people mentally rotate alphabetic letters, not just objects.

Q: What is the Symbolic Distance Effect (Paivio, 1975)?

A: Size judgments are faster when differences are larger (e.g., elephant vs rabbit); judgments slow when objects are depicted incongruently with real size.

Q: What is Kosslyn’s Theory of Imagery (v1.0)?

Proposes a spatial buffer like a monitor: limited extent, images fade, resolution highest at the center, and small details are hard due to the buffer’s “grain.”

Q: What are Image Files in Kosslyn’s Theory?

: Stored “pictures” of objects that can be zoomed, rotated, scanned, and moved

Q: What are Propositional Files in Kosslyn’s Theory?

A: Contain abstract information describing how to construct and manipulate images via links between image files

Q: What are Scanning Experiments (Kosslyn)?

A: Found that scanning time between points in mental images increases with the actual distance, supporting analog representation.

: What did Kosslyn (1973) show with animals of different sizes?

: People took longer to focus on rabbit details when imagined next to an elephant versus a bee, suggesting limits in the spatial buffer.

: What did Kosslyn, Ball, and Reiser (1978) show with mental maps?

A: Reaction time to mentally travel between map points increased with actual distance between locations.

Q: What is the Imaginal Ponzo Illusion (Wallace, 1984)?

Both imagined and real Ponzo illusions produced the same perceptual effect, supporting equivalence of imagery and perception

: What is Pylyshyn’s Criticism of Analog Theory?

Argued imagery is an epiphenomenon; results are influenced by demand characteristics; storing images would require immense capacity; information may be stored as modality-free propositions instead.

Q: What is Propositional Representation?

A: Information is stored as relations (e.g., size, distance, direction), not literal pictures (an elephant’s representation is not “larger” than a mouse’s in the brain).

What did Chambers & Reisberg (1985) show with reversible figures?

Participants could only interpret figures one way in imagery; reinterpretation required drawing them, suggesting images differ from pictures.

: What are Heuristics in Cognitive Maps?

: People distort maps using biases: right-angle, symmetry, rotation, alignment, and relative-position heuristics.

What did Roland & Friberg find about imagery and perception?

PET scans showed visual imagery activates occipital, parietal, and temporal areas; auditory imagery activates auditory association cortex.

What did Logie et al. (2011) find about high vs low imagers in mental rotation?

High imagers use visual and premotor cortex; low imagers use supplementary motor cortex and make more errors on large rotations.

What is the difference between the “What” and “Where” streams?

“What” stream processes form and color; “Where” stream processes movement and spatial location.

What imagery/perception deficits are linked with brain damage?

Where” stream damage: trouble locating objects and describing spatial layouts. “What” stream damage: trouble recognizing or describing objects from memory, but intact spatial imagery.

What is Prosopagnosia in imagery

Impaired ability to recall or imagine familiar faces, though object imagery may be intact.

What is Cerebral Achromatopsia in imagery?
A: Impaired ability to imagine or recall color information (e.g., might say “elephants are green”).

impaired ability to imagine or recall color information (e.g., might say “elephants are green”).

What are Extremes of Visual Imagery?

Aphantasia: absent or weak imagery, poor autobiographical memory (prevalence ~3.9%). Hyperphantasia: extremely vivid imagery, often “as real as seeing.”

What are key characteristics of Aphantasia (Zeman et al., 2021)?

Preserved spatial skills, but poor object imagery, weaker autobiographical memory, introversion, autistic traits, and reduced connectivity between prefrontal and visual cortex

What was the estimated prevalence of Aphantasia (Dance et al., 2022)?

~3.9% have weak imagery, ~0.8% have completely absent imagery