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