Introduction to PsychologySuzy Scherf

Lecture 8: How Do We Know?

Sensation and Perception Early Memory

What are Our Senses For?

• Vision

• Audition/Hearing

• Smell

• Taste

• Somatosensory

• Vestibular

All the senses designed to -

What are Our Senses For?

Transduction by Design

1. Eyes designed to transduce

2. Auditory apparatus designed to transduce

3. Tongue and Olfactory apparatus designed to transduce

4. Sensory receptor in the skin, organs, joints, bones all designed to transduce

Transduction by Design

If we thought that a “sixth sense” existed, we would have to figure out -

What are Our Senses For?

• Our senses have evolved to -

• Our senses provide the necessary information -

Vision

• Processes electromagnetic energy –

• Electromagnetic energy travels -

• Vision is a -

Visual Spectrum of Light

• Includes wavelengths of light that -

• Includes wavelengths of light that -

Anatomy of the Eye

Photoreceptors in the Retina

Visual Pathway

Visual Pathway

Optic Chiasm

ThalamusOptic

Radaitions -

Audition

• Objects produce vibrations that -

• Auditory systems detect -

• Analysis of these sound waves -

Ear Apparatus for Hearing

Auditory Receptors

Spectrum of Audible Sound Waves

• Provide a source of info -

• Low freq. waves travel ________ than short freq. waves

• A consequence of natural selection

• Elephants vs. Insects

Chemical Senses

• Seen in all animals and are likely to be most important of the senses and the first to evolve

• Animals that live in the sea -

• Smell evolved when -

Taste

• Only a contact sense -

• Provides animals with -

• Not only via the tongue -

Taste

Taste

Taste

1. Salty –

2. Sweet –

3. Sour –

4. Bitter –

• ________ sense

Smell

1. 2.

• provides animals with an ability to detect

• discerning chemical composition of substances -

Smell and Taste

Sensory Apparatus for Smelling

Sensory Apparatus for Smelling

Somatosensory

• Detects -

• Specialized response to extremes -

• Pain –

Somatosensory Receptors

Vestibular

• Sensitive to -

• Provides info about -

• Liquid in ear canals -

Ear Apparatus for Vestibular Sense

Human Vestibular Cortex and Out-of-Body Experiences

Blanke et al. (2002)

Seizure center

Motor responses Bodily Sensations

Auditory Sensations

OBE

“I see myself lying in bed, from above, but I only see my legs and lower trunk.”

Elements of all Sensory Systems

1. Specialized sensory receptors that are designed specifically to transduce a particular kind of physical energy.

2. Specialized neural circuits that channel the sensory information through the Thalamus to the relevant Primary Sensory Cortical Areas

Elements of all Sensory Systems

3. Maps at all levels of the brain hardware that represent and organize the sensory information so that it will mirror the physical world

Including:

What is Perception For?

• ____________ sensory information

• Perception reflects the real world -

What is Perception For?

• Designed to -

• Tight link with memory -

Perception Designed to Guide Action

• Example: How do we avoid bumping into things?

Possible answers:

Perception Designed to Guide Action

• Example: How do we avoid bumping into things?

Actual answer:

Perception Designed to Guide Action

• Example: How do we avoid bumping into things?

Distance from eye (meters)

Siz

e of

imag

e on

ret

ina

(mm

)

Perception

• Most of the time perception leads animals to -

• Perceptual mechanisms have evolved to -

• Even though perceptions are derived in large part from transduced info that has been re-represented in the brain.

Sensory and Perceptual Systems are Modularized

• They are specialized to -

• Most of these systems have -

• Early deprivation of activity -

Sensory and Perceptual Systems are Modularized

• Then passed on to higher-order regions of the brain -

• Parietal Lobe –

• Temporal Lobe –

• Frontal Lobe –

Dorsal Pathway -

Ventral Pathway -

Integrating Perceptual Info

• When info processed and sent onto other systems for analysis - things can go awry.

• The case of Synesthesia

Synesthesia

• Syn = ___________ + aisthesis = ___________

• Means joined sensation -

• Music that looks like shards of glass

• Involuntary, but triggered by stimulus -

• Can be temporarily induced by -

Synesthesia

• Tends to run in families, more women than men, and left-handed

• Excellent memory but poor spatial and mathematical skills

• Prone to unusual experiences like those of temporal-lobe epileptics - déjà vu, clairvoyance

Synesthesia - Neural Basis

Synesthesia

• May reflect a holistic process of perception that is not usually available to consciousness - but is totally normal - some evidence in kids

• Clearly demonstrates how sensation, perception, emotion, and memory working together to interpret our environment

What do We do with Perceptual Info after We Integrate and Act?

• Keep track of it for future use?

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Memory - What’s it for?

Why don’t we remember everything about all our past experiences?

1.

2.

Memory - What’s it for?

Why don’t we remember everything about all our past experiences?

3.

4.

Memory - What’s it for?

For our memory systems to function efficiently we have to forget much of our experience or ignore it all together (ie. never encode it).

Example: Change Blindness

Change Blindness - What’s Important for Us to Remember?