PSYC 2410 Study Guide - Final Guide: Memory Span, Cochlea, Complementary Colors

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Lecture 9: Exteroceptive Sensory Systems
- Reception of information from outside the body
- Sensation: the process of detecting a stimulus (receptor).
-
- Perception: the higher order process of integrating, recognizing, and interpreting
patterns of sensations
- Hierarchical organization:
o Receptors Other structures (e.g., thalamic nuclei) cortical processing
(primary/secondary sensory cortexes, association cortex)
- VISION
o Produces an internal representation of the outside world
Not always an accurate representation of reality
o A perception of reality thats based on specific receptors (hardware)
Differences in species:
Interspecific: snakes can see IR, insects see UV
Intraspecific: colour blindness
Attention, interest, experiences, and other factors can all affect how we
perceive something
o Perception of light:
Light: electromagnetic wave of energy that can be represented by
discrete units/particles of energy called photons
Travel very fast (300,000 km/s)
Humans see at a wavelength of 380-700 nanometres
Wavelength = colour
Intensity of light = brightness
o Bright red = high intensity 700nm wavelength light
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- Iris: contractile tissue that regulates size of pupil
o Wide pupil = more light sensitivity = less acuity (ability to see fine details)
o Narrow pupil = lower light sensitivity = higher acuity
- Binocular Vision
o Two eyes
o Lateral very wide field of view
o Frontal much smaller field of view
o Frontal eyes 3D (depth and distance)
o
o Binocular disparity: the difference in the position of the retinal image of the
same object on the two retinas
Greater binocular disparity for closer objects
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- Presbyopia: reduced ability to focus on near objects with age
o Lens is less flexible
Need glasses for reading (convex lens)
- Cellular structure of the retina:
o Layers (in order): Retinal ganglion cells, amacrine cells, bipolar cells, horizontal
cells, photoreceptors (cones and rods)
o Retinal neurons communicate both chemically via synapses and electrically via
gap junctions
o The retina is inside out… light reahes the reeptor laer ol AFTER passig
the other four layers. The receptors receive this info and then send it back out
o Issues:
Light is distorted by the retinal tissue when it is coming in.
Reduced by an indentation at the centre of our retina called the
fovea
Because of the gap in the receptor layer (needed for retinal ganglion cell
axons that leave the eye), there is a blind spot.
Our visual system fills in the image for us (COMPLETION)
- Eye Movement:
o Saccades: very quick eye movements
Temporal integration: the visual system temporally integrates many
subsequent images grabbed by the moving eye into one big, wide angle,
colourful perception of the world (summation of recent visual
information)
A stabilized retinal image would result in a disappearing image
- Photo Receptors (cones, rods)
o Night active, nocturnal species: great prevalence of rods
o Day active, diurnal species: great prevalence of cones
o Duplexity Theory of vision
Scotopic Vision: rod mediated
High convergence high sensitivity and low acuity
In low lighting, the weak signals picked up by several receptors
can add up
Lacks the detail and colour of photopic vision
Photopic vision: cone mediated
Low convergence low sensitivity and high acuity
More intense signal required to activate RGC (idk what this is)
Colour vision is mediated by cones
o Visual Transduction
Transduction: conversion of one form of energy into another
Visual transduction: light neural signals
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