Perception - COGS 200

Lecture 11-15?

How does visual info travel from the eye to brain?

Goes through retina → optic nerve, chiasm, tract → thalamus → primary visual cortex

What are feature detectors?

System responding to presence of specific pattern in stimulus

Ex. Specific shape, colour, direction of motion

What is the ventral stream, pathway, and what lobes does it consist of?

Vision for perception, the what pathway and temporal lobes

What does the ventral stream do?

Connect sensation to memory

How do visual illusions occur?

Perceptual system method for using shortcuts to process things more efficiently is tricked when inaccuracies violate regularities

What is size constnacy?

When something far from retinal casts same size retinal image as something close

What is the terror subterra illusion?

Two monsters, further one looks bigger even though same size

What theory gives rise to afterimages and how do afterimages work?

Colour opponent theory, where cells with specialized stimuli after long exposure become fatigued

What is the troxler fading theory?

We stop processing static things and eventually stop perceiving them at all as it is more efficient to handle new info worth processing

What are some more visual illusion?

Motion induced blindness

Apparent motion

Lilac chaser; combo after images and apparent motion

Flashing light (Magic Light)

Shadow cues

How do ventral aspects determine what a face is based on invariant and changeable aspects?

Invariant; 2 eyes, nose, mouth

Changeable; expressions

Why does the hollow mask illusion work?

Our experience with face perception and incomprehension of things like an inverted nose causes it to be seen

What is prosopagnosia?

Inability to recognize faces

What is pareidolia?

Seeing faces where they don’t exist

What is the dorsal steam, pathway, and lobe?

Vision for action, how pathway, parietal lobes

Who is patient DF?

Person who had bilateral damage in ventral visual stream, visual form agnosia

What is the ebbinghaus illusion?

Circle moving in a circle illusion

WHat are some action intentions affecting vision?

Can detect change in large objects quicker with power grip

Can detect change to small object quicker with precision grip

What is the perihand (space)?

Space near or around hands, improves visual processing when have lesions/brain damage if move into perihand space

What is classical cognitive science?

Computational theory of mind - view that mind is like a computer

What is a turing machine?

Abstract computational machines which manipulated symbols according to rules and internal states

What is the stroop effect?

Delay in reaction time between congruent and incongruent stimuli

What is semantic interference?

Longer reaction if colour of word mismatches meaning of word

What is semantic facilitation?

Faster reaction times if colour of words matches meaning of word

What is the McGurk effect?

Perceived, audio, visual saying all hear/see different things

How can tactile info interferes with speech perception?

English has some tiny bursts of aspirations which may cause people to mishear

What was the study of visuo-tactile integration in speech?

Associations are learnt very early in language acquisition where puffs of air indicates aspiration

• Exists in infants too

What is the phonemic restoration effect?

Missing speech sounds are restored by brain and appear to be heard

• Brain interprets ambiguous auditory signal as an unambiguous signal

  • Doesnt occur whne phonemes are just missing

How does the auditory brain activate without auditory input?

Brain areas associated with auditory processing activate even when peple view silent visual speech

What is voice onset time?

Movemeent of physical mouth lips to vocal chords

What is perceptual narrowing?

Ability to perceieve something despite being rarely exposed to it (infants and human langauges they don’t know)

What was the Warren Perceptual Restoration missing speech sounds experiemnt?

Undergrads given stimulus of a tape recording of a sentence with a cough replacing a phoneme → asked to identify cough location but none succeeded

What was Daivd Lewkowics and Amy Hansen Tift study of infant eye gaze?

Had monolingual infants look at someone utter english monologue and tracked where infant looked at

Results for monological infants for study on infant eye gaze?

4 months; loooked longer at eye

8 months; looked longer at mouth

12 months; looked at equal time

What was Ferran Pons and Laura bosch study on infant eye gaze?

Same as Lewkowics and Tift’s,except bilingual

Results from Pons and Bosch study?

4,8,12 months similar results for dominant language

For secondary langauge

• 4 months; equa

• 8 months; longer mouth

• 12 months; longer mouth

What is the distinction between seeing objects vs seeing facts?

Seeing objects; perceiving physical entities

Seeing facts; knowing what is seen means something

What is epistemology?

Knowledge, truth, memory, and perception

What is the difference between mediated and direct knowledge?

Mediated/indirect knowledge requires inferences, reasoning, and may be incorrect if inference is incorrect

Direct knowledge comes immediately from perception

What is the skeptical argument of visual perception, and Dretske’s response?

If perception is mediated by subjective expereinces can we ever be certain of what we see

• can still see objects even if not sure what they are

What is the view, key idea, and objection to direct realism?

View; we perceivie objects directly as they exist in the world

Key idea; objects exist indp of our perception and we see them as they truly are

objection; ignores illusions, hallucinations, and perceptual distortions

What is the view, key idea, and objection to representative/indirect realism?

View; we don’t directly pperceive objects but rather perceive mental representations of them

Key idea; our brains make internal representaitons of world based on sensory input (ex. play game not seeing game but rather image of it)

Objection; if only perceive representations, how can confirm accurate reflection of reality

What is the view and objection to idealism/phenomenalism?

View; no external reality all things are mental constructs

Objection; radical view not rly accepted as implies reality does not exist outside of minds

What is the view and problems to the mixed/hybrid position?

View; may see physical objects directly (direct realism) but only know them through mental processing (indirect realism)

Problem; how do we know how objects look without perceiving our own internal mental images

What is sensory perception?

Seeing an object without knowing what it is

What is cognitive perception?

Recognizing an object as what it is

What is optic ataxia?

When dorsal path is damaged but ventral is not

What is visual form agnosia?

If ventral pathway is damaged but dorsal is not

What is epiphenomenal qualia

Mental states/qualia are caused by physical events in the brain

What does Frank Jacksona argue?

A fully objective physical account of mind is incomplete

• Physical facts are not all the facts there are about minds

What is spectrum inversion?

Same object should make several different ideas in each person at same time due to private and subjective experience of things

What is Nozick’s experience machine?

Should you plug into an expereince machine that gives any experience desired whilst floating in a tank

• Nozick says no as argues desire to do things is greater than simply experiencing doing them

• Cypher from matrix says yes as ignorance is bliss

What is the grand illusion?

Ability to acquire and maintain a complete and accurate representation of the scene before us

What is the cutaneous rabbit?

• Subject rests arm on cushion and tappers tap 2-3 locations on arm

• 5 taps on wrist, 5 on forearm, 5 near elbow

  • Felt as if a tiny rabbit were hopping from wrist to elbow

What is the picket fence effect?

• Alternating 50 milli-sec bursts of soft pure tones and loud band noise

  • Report pure tone as continuous

    • tone/scene completes itself

    • Acoustic tunnel effect

How does audition influence taste?

Chips are seen as crisper and frasher with louder bite sounds and higher frequencies

How does vision influence touch?

Drumstick experiement where participants must judge which hand tapped first

• do well with hands in natural position

  • with hands or sticsk crossed, vision and touch conflicts make jdugement more difficult

How does change blindness occur?

• Initially complete sensation but quickly forgotten

• Not representation but comparison that fails

• Initially complete sensation is recoded in a way that precludes comparison

• Regardless of gaps, perception is a process/computation

What is predicitive coding?

Perception model of loop between predicting testing and correcting