PSYCH 104 Midterm 2 (The eyes and conciousness) Flashcards
Visible light: What wavelengths can we see?
Visible light:
- Electromagnetic radiation between 400 and 700 nanometers
Hue:
Hue:
- The colour of light
The cornea
- The cornea
○ Part of the eye containing transparent cells that focus light on the retina
§ Myopia (nearsightedness)
□ The cornea is too long causing the focus of light to be Infront of the retina
§ Hyperopia (farsightedness)
□ Cornea is too flat causing the focus of light to occur behind the retina
The lens
- The lens
○ Part of the eye that changes curvature to keep images in focus
○ Contains transparent cells
○ Accommodation:
§ Changing the shape of the lens to focus on objects near or far
The retina
- The retina
Membrane at the back of the eye responsible for converging light into neural activity
Rods
○ Rods
§ Photoreceptor cells in the retina allowing us to see in low levels of light
□ Dark adaptation: time in dark before rods regain maximum light sensitivity
Cones
○ Cones
§ Photoreceptor cells in the retina allowing us to see in colour
§ More rods than cones
Photopigments
○ Photopigments
§ Protein molecules within the rods and cones whose chemical reactions when absorbing light result in nerve impulses being generated
Optic nerve
○ Optic nerve
§ Nerve (technically a bundle of ganglion cells) that travels from the retina to the brain
Peripheral vision and nighttime
Peripheral vision and nighttime
- We have more rods that align with our peripheral vision
- Therefore we can see in the dark better with our peripheral vision than our central eye
The eyeballs -> to the brain (what happens?)
The eyeballs -> to the brain
- On its way to the brain the sensory nerves cross over from right to left and left to right
The blind spot
The blind spot
- Part of the visual field we cant see because of an absence of rods and cones
Hubel and Wiesel (What did they do?)
○ Hubel and Wiesel
§ Records electrical activity of V1 area of visual cortex in cats
§ Discovered feature detector cells:
□ Cells that detect lines and edges
At later levels of visual processing (like V2) cells begin to detect more complex shapes and movements
The principles of gestalt psychology (What are they?)
- The principles of gestalt psychology
○ A Germán school of psychology that emphasizes the natural organization of perceptual elements into wholes, or patterns
○ “gestalt” = “whole”
○ Psychology should be focused on how the “whole” is created from its basic parts
○ Main figures in perception
§ Max Wertheheimer
§ Wolfgang Kohler
§ Kurt Koffka
The principles of gestalt psychology
○ Proximity
- The principles of gestalt psychology
○ Proximity:
§ Objects physically close to each other tend to be precieved as unidentified wholes
The principles of gestalt psychology
○ Similarity
- The principles of gestalt psychology
○ Similarity:
Similar objects will be seen as being grouped together or related
The principles of gestalt psychology
- Continuity
- Continuity:
○ We precieve lines as continuous movement while discounting abrupt changes
Also called “good continuation”
The principles of gestalt psychology
- Closure
- Closure:
○ The tendancy to view incomplete figures or forms as complete objects
The principles of gestalt psychology -
Symmetry
- Symmetry:
○ Symmetrically arranged objects are perceived as wholes
The principles of gestalt psychology -
Figure-ground segregation
- Figure-ground segregation
○ The tendancy to separate elements of a image into a foreground (figure) and its background (ground)
- Trichromatic theory:
- Trichromatic theory:
○ Idea that colour vision is based on our sensitivity to the three primary colours
○ Fits with later findings that three types of cone cells are present that respond maximally at different wavelengths
§ Short
§ Medium
§ Long
○ Relies on additive colour mixing
○ Cant account for afterimages
Opponent process theory
- Opponent process theory:
○ Theory that we perceive colours in terms of three pairs of opponent colours
§ Red or green
§ Blue or black
Black or white
Dual-process theory
- Dual-process theory:
○ The modern colour version theory that posits that cones are sensitive to red, green, and blue as well as opponent processes at the level of ganglion cells
Colour blindness
Colour blindness
- Inability to see some or all colours
- Usually due to genetic abnormalities that cause the absense/reduction in a specific cone type
○ Monochromats - only have one type of cone (very rare however)
○ Dichromats - have two types of cone
- Brain damage to cortical areas responsible for vision can also produce colour blindness
- Depth perception
- Depth perception
○ The ability to judge distance and three dimensional relations
§ Monocular cues:
□ Stimuli that enable us to judge depth using only one eye
§ Binocular cues:
□ Stimuli that enable us to judge depth using both eyes
Monocular cues
- Relative size:
Monocular cues
- Relative size:
○ All things being equal, more distant objects look smaller than closer objects
Monocular cues - Texture gradient
- Texture gradient
○ The texture of objects becomes less apparent as they are farther away
Monocular cues - Interposition
- Interposition
○ Close objects block the view of distant objects
Monocular cues - Linear perspective
- Linear perspective
○ The outlines of objects converge as distance increases
Monocular cues - Height in plane
- Height in plane
○ Here distant objects tend to appear higher and nearer objects appear lower
Monocular cues - Light and shadow
- Light and shadow
○ The casting of shadows vives objects a 3-D form
Monocular cues - Motion parallax
- Motion parallax
○ When objects loving across a field of view appear to move more the closer they are to an observer
Binocular cues - Binocular disparity
Binocular cues
- Binocular disparity
○ Depth information is obtained by comparing the difference in image location of the left and right eyes
Binocular cues - Binocular convergence
- Binocular convergence
○ The degree to which your eyes converge inward gives provides information to estimate distance
Blindness (vision loss)
Blindness (vision loss)
- The inability to see due to problems with the eye and its related structures
- Vision is less than or equal to 20/200 (20/20 is considered normal vision)
- Rely more on other senses (touch, hearing, etc.)
- Visual cortex’s function changes due to neural plasticity
Motion blindness (Cerebral Akinetopsia)
- Motion blindness (Cerebral Akinetopsia)
○ Neurological disorder in which a person is not able to perceive motion
○ Often caused by
§ Brain damage
§ Alzheimer’s disease
- Visual agnosia
- Visual agnosia
○ A failiure to recognize visually presented objects
§ Not due to impairments in memory or intelligence
○ Often due to damage to peripheral regions of occipital cortex near the parietal and temporal lobes
- Visual agnosia (What are the 4 types?)
○ Different types
§ Prosopagnosia: failiure to recognize faces
§ Anosognosia: cant recognize illness
§ Finger agnosia: cant recognize fingers
§ Topographical disorientation: cant recognize places
- Blindsight
- Blindsight
○ The ability of individuals with blindness to detect and respond to visual stimuli despite lacking awareness of having seen anything
○ Often the result of damage to V1 area of visual cortex
Conciousness (What is it?)
- Conciousness:
○ The moment to moment subjective experience of the world, bodies and mental sensations
§ Subjective
§ Dynamic
§ Self-reflective
○ Interdisciplinary:
§ Physics, philosophy, psychology, neuroscience, computer sciences
○ How is it measured?
§ Self-reports
§ Physiological measures
§ Behavioral measures
Cognitive psychology
- The analogy
Cognitive psychology
- The analogy
○ Humans are “information processors” the “mind” is the computers software and the brain is the computers hardware
§ Caveat: this is an oversimplification and not all cognitive psychologists agree with this interpretation
- Controlled (effortful) processing:
- Controlled (effortful) processing:
○ Mental processing that requires some degree of volitional control and attentiveness
§ Voluntary use
§ Slow but flexible
- Automatic processing:
- Automatic processing:
○ Mental activities that occur automatically and require no or minimal conscious control or awareness
§ Minimal conscious processing
§ Fast but static
Divided attention:
Divided attention:
- The ability to perform more than one activity at the same time
○ Difficult if tasks require similar cognitive resources
§ Example: like listening to music and studying for an exam
