Chapter 4: Sensation, Attention, and Perception

Transduction

-is conversion

-It refers to the process of converting sensory information into neural signals

Psychophysics

The science of establishing quantitative and measurable relationships between physical stimulation and psychological events

Absolute Threshold 

The lowest level of sensory strength necessary for detection

Ex: hearing a watch ticking 20 ft away

Difference Threshold

• The minimum amount of change in a stimulus that an individual can detect

• AKA the “Just noticeable difference.”

-Ex: changing coca cola bottle (new logo)

-Ex: reducing the size of the chocolate bar so that the company can earn more money

Transduction: Selection and Limitation

Data selection system

Which information to code and send to the brain

Lack of specific transducers

total loss of some sensations like color blindness, hearing loss, sense disorders, etc

Restricted range of transducers

damaged or partially functioning of senses

Sensory adaptation

Sensory receptors become less responsive to constant stimuli over time

ex: unaware of how bad your house smells like

ex: ignoring the a/c sound

Feature detection

allows selective detection of edges, shapes, colors, movement, and more

• the corner of a building

• the edge of a road

Vision- An Overview

The eyes transduce only a tiny fraction of the range of electromagnetic energies, called the visual spectrum

Hue

Various colors of light correspond with wavelengths of the light that reaches our eyes

Saturation

The purity of the hues. Hues from a narrow band of wavelengths are saturated, or pure.

Brightness

The amplitude, or height, of light waves. Waves with greater amplitude carry more energy and cause colors to appear brighter or more intense.

Basic Anatomy of the Eye

Cornea

Frontmost clear window of the eye; bends light inward to help focus

Lens

Located behind the pupil; adjusts curvature to focus light on the retina

Optic Nerve

The cranial nerve that transmits visual information from the eye to the brain.

Photoreceptors

-This is where the Transduction occurs:

-convert light energy into electrical signals that the optical nerve can send to the brain 

Cones

Produce color sensations and fine details

Rods

Cannot detect color, but more sensitive to light than cones - dark adaptation

Limitations of Our Sight

• Limited Visual Spectrum

• Eyesight worsens with age

• Eye Conditions

• Reliant on attention and focus

• Pattern-seeking bias

• Vulnerability to deception and misperception (optical illusions)

Characteristics of Sound (know)

Sound travels in a series of invisible waves of compression (peaks) and rarefaction (valleys)

Frequency (don’t need to know)

The frequency of sound waves corresponds to the perceived pitch of a sound.

Amplitude (dont need to know)

Height of a sound wave indicates energy, which corresponds to a sense of loudness or sound intensity.

Pinna

Visible part of ear that focuses sound into ear canal

Eardrum

Vibrates in response and transmits inward to the ossicles, creating vibration

Cochlea (Know)

contains hair cells that convert sound waves into electrical impulses that are carried along the auditory nerve to the brain.

The transducer of the ear!

Conductive hearing loss (know)

• The transfer of vibrations from the outer ear to the inner ear weakens. 

• May be caused by disease or injury to the eardrums or ossicles

Sensorineural hearing loss (know)

• Damage to inner ear hair cells or auditory nerve

• Noise-induced

  • Ex: earbuds being blast loudly in ears

Chemical senses (know)

Olfaction (smell) and gustation (taste)

• Think “face”

Somesthetic sense (know)

Those related to our ability to “feel”

-Think “body”

• Touch senses (skin)

• Kinesthetic senses (receptors telling us the position of our body parts)

• Vestibular senses (balance, motion, and spatial orientation)

Transduction

Air enters the nose, where nerve fibers may be stimulated to create an action potential that then travels to the brain

Olfactory fatigue

the temporary loss of smell senitivity after prolonged exposure to an odor

Nose blindness

-think of sensory adaption transduction

Anosmia

The inability or severe loss in ability to smell specific or all odors (usually due to colds, sinus infections, exposure to strong chemicals, or othe medical issues). This loss can be temporary or permanent

-Think or restricted and lack of specific transducers. 

Lock-and-key theory of olfaction

receptors may bind with airborne chemical molecules that have matching “shapes”

Taste buds

Taste-receptor cells are located mainly on the top side of the tongue, especially around the edges

Characteristics of Taste

1. Sweet

2. Salty

3. Sour

4. Bitter

5. Umami (brothy or meaty)

Mechanoreceptors

They are sensory receptors that detect touch-related stimuli, such as pressure, touch, and sound waves. They are found in the skin, muscles, joints, and inner ear

Gate Control Theory

Pain messages from two different types of nerve fibers pass through the same neural gate in the spinal cord.

• If the gate is closed by one pain message, the other may not be able to pass through

  • Ex: stubbing your toe or burning your hand on a stove would temporarily override or reduce pain felt from other sources like a headache or joint pain

Characteristics of Touch

1. Light touch

2. Pressure

3. Pain

4. Cold

5. Warm

Multimodal Integration

Our tendency to integrate sensory impressions from multiple modalities

• Can create a more cohesive understanding of our environment

• Mismatches can cause adverse effects such as disorientation and motion sickness

Inattentional blindness

Failure to notice the stimulus because attention is focused elsewhere

Ex: focusing on the ball

Change blindness

Failure to notice the background is changing because we are focused on one specific element of the scene

Selective attention

Our ability to focus on specific sensory input

Attentional resources are limited

• Attempts to divide can result in poor consequences

• Not possible to do multiple things at one time when greater focus is required

• Requires task-switching: moving attention rapidly between things

Mind-wandering

The tendency for attention to stray to things that are internal and unrelated to stimuli

The Process of Perception

When the brain organizes and interprets sensory impressions into meaningful patterns.

Illusions

Occurs because of perceptual misconstruction in the way information is sent to the brain

Halluncinations

People perceive objects or events with no external reality

Synesthesia

Clinical condition in which sensory impressions cross sensory barriers

Ex: Seeing the color purple and tasting grapes

Depth perception

Ability to see space and accurately judge distances allows us to construct a 3-D experience

• Occurs around 5 months old

Virtual reality (VR)

Artificial computer-simulated environment that is perceived in three dimensions through the use of a special headset

• used in clinical psychology

• Veterans and others with PTSD

Alternate States of Consciousness

Fatigue, delirium, hypnosis, meditation, euphoria, and drugs

Drugs

Stimulants, Depressants, and Hallucinogens