Chapter 4 Flashcards
Sensation
The process of detecting external events with sense organs and turning those stimuli into neural signals
Ex. Air pressure in eardrum >sound
Light stimulating receptors in eye >vision
Perception
Directing attention toward, organizing, and interpreting stimuli
Transduction
-The process of turning physical energy (raw sensation) into electrical impulses to be interpreted by brain
-Sensory receptors involved in transduction are different for each sense
-Forms our internal representation of world
Psychophysics
Explores how the changes in intensity of physical energy (eg light sound) is related to psychological experience
Absolute Threshold
-Minimum amount of energy or quantity of a stimulus required to be reliably detected at least 50% of the time it is presented
-Varies across individuals
Difference Threshold
-Smallest difference between stimuli that can be reliably detected at least 50% of the time
-aka just noticeable difference
-Related to the intensity of the original stimulus >more intense original stimulus requires larger change to detect difference
Weber’s Law
The just noticeable difference between two stimuli changes as a proportion to those stimuli
Ex.
A: Volume =50 JND = 5
B: Volume =100 JND = 10
C: Volume =150 JND = 15
Divided Attention
Attention directed to more than one stimulus or task at the same time
Selective Attention
Focusing on one particular event or task
Inattentional Blindness
Failure to notice obvious events or objects because attention is directed elsewhere
The Human Eye
-Primary function is to gather light and change it into neural signals (action potentials)
-Light travels in waves
-Differences in wave lengths correspond to different colour
>Long =red
>Medium = green
>Short = blue
-Differences in amplitude correspond to brightness
>Low amplitude = dim colours
>High amplitude = bright colours
Path of Light Through Eye
- Light entering eye is bent by cornea before passing through pupil
- Pupil regulates amount of light entering eye by expanding/shrinking (controlled by iris muscle)
- Light passes through the lens which changes shape to focus light onto back of eye
- Light is focused on retina (layer of cells on back of eye that converts light into neural signals >transduction)
- Photoreceptors:
Cones: colour vision, high acuity
Rods: sensitive under low light levels, no colour, low acuity - Rods and cones send messages to ganglion cells, where the messages are organized and sent to brain via optic nerve
Fovea
-central region of the retina
-densely packed cluster of cones
-surrounded by rods
Visual Cortex
Dorsal Stream(Up)-Visually Guided Action
Ventral Stream(Down)-Perception/Object Recognition
Function of Ear
To capture sound waves
Sound Waves
Changes in mechanical pressure through a medium (ie solids, liquids, or gas)
Frequency = Wavelength
-Measured in hertz (Hz)
-The number of cycles a sound wave travels per second
Pitch
Perceptual experience of sound wave frequencies
High vs Low Frequency Sounds
High-frequency sounds->Short wavelengths, high pitch
Low-frequency sounds ->Long wavelengths, low pitch
Humans able to detect frequencies from 20Hz - 20 000 Hz
Amplitude = Perceived Loudness
-Higher amplitudes -> louder
-Lower amplitudes -> quieter
-Loudness measured in decibels (dB)
-Humans able to detect noise levels above 20 dB
Outer Ear
-Sound waves enter the Pinna and travel through the auditory canal
-Sound waves cause the eardrum to vibrate
Middle Ear
Ossicles
-Malleus (hammer)
-Incus (anvil)
-Stapes (stirrup)
Moves together with the drum
Inner Ear
Cochlea
-Fluid filled membrane
-Coiled, snail-like shape
-Hair-like projections line
basilar membrane within cochlea
-Projections convert sound to
neural impulses (transduction)
Basilar Membrane
Movement of the hair cells stimulate auditory nerve cells
Auditory Nerve
Sends messages to the thalamus
Pitch Perception
-High frequency sounds stimulate hairs close to the ossicles
-Low frequency sounds stimulate hairs farther along the membrane
Place Theory of Hearing
How we perceive pitch is based on location(place) along basilar membrane stimulated by sound
Frequency Theory
Perception of pitch is related to frequency at which basilar membrane vibrates (how many times the hair cells are stimulated)
Primary Auditory Cortex
-Responsible for sound processing and perception
-Distribution of cells organized by specific frequencies
Secondary Auditory Cortex
Interpretation of complex sounds
>speech and music
Vestibular System
Sensory system within the ear that provides information about spatial orientation and motion of the head
(Head placement and movement)
Vestibular Sacs
Structures that influence your ability to detect when your head is not upright
Cilia embedded in liquid line the bottom of the vestibular sacs
When head is tilted, the fluid moves and bends the cilia-> Neuronal signals are sent to the brainstem
Semicircular Canals
-Three fluid-filled canals found in the inner ear that respond to head movement
-Up-down, left-right, forward-backward
-Ampulla
->Enlarged area at the base of each canal containing cilia embedded within fluid
-> Fluid movement bends cilia: Sends neural message to brainstem
Vestibular Ganglion (nerve)
Transmits information from inner ear to brainstem, from which it influences various processes and behaviours,eg
>Autonomic nervous system
>Amygdala
>Insula (integration of visual, somatosensory, vestibular information)
-Conflicting inputs from visual and vestibular systems>motion sickness
Taste: Gustatory System
Primary Tastes
Salty, sweet, bitter, sour
Umami (“savouriness”)
The Tongue
-9000 taste buds(receptors) inside papillae (bumps on the tongue), although number varies among individuals
-Sensory neurons transmit signals from tastebuds to the gustatory cortex and the secondary gustatory cortex (pleasurable experiences associated with food) in the brain
-‘Blind spot’ in the middle of the tongue has very few taste receptors
-Taste receptors are replaced approx every 10 days
Smell: Olfactory System
Smell
Detection of airborne particles via specialized receptors located in the nose
Olfactory Epithelium
-Thin layer of cells in the nasal cavity
-Lined with sensory receptors called cilia (tiny hair-like projections)
Num Different Types of Odour Receptors
Humans have approx. 1000 different types of odour receptors, but can identify 10 000 different smells
>Experience of particular smell is produced by pattern of stimulation of odour receptors
Olfactory Bulb
-Cilia send messages to Neurons in the Olfactory Bulb (skips thalamus)
-Olfactory Bulb
>Brain’s central region for processing smells
>Located on bottom surface of frontal lobes
>Connects to several other brain regions through the olfactory tract
-Areas involved in processing emotion and subjective experience (pleasure versus disgust)
Olfactory System
Cilia of the Olfactory epithelium ->Olfactory bulb ->Olfactory tract
->Brain regions involved in higher processing
Haptics
-Transmission and understanding of sensory information via touch
-Active
-Exploratory
>Receptors are in skin
Kinesthesis
Receptors in muscles, joints and tendons transmit information about movement and body position to the brain
Nociception
-Activity of nerve pathways that respond to uncomfortable or painful stimulation
>eg. sharp stimuli, hot temperatures
-Pain receptors are called nociceptors
-Cognitive, sensory and emotional factors all interact to influence our perception of pain (nociception)
