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Absolute Threshold
The minimal intensity needed to just barely detect a stimulus.
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Just Noticeable Difference
The minimal change in a stimulus that can just barely be detected.
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Sensory Adaptation
- Sensitivity to prolonged stimulation tends to decline over time as an organism adapts to current conditions.
- Our systems emphasize change in responding to sensory events.
- A stimulus that doesn't change usually doesn't require any action.
- Examples are feeling our clothing or hearing sounds around us or tuning these things out.
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Cones
- Photoreceptors that detect color, operate under normal, daylight conditions, and allow us to focus on fine detail.
- Densely packed in the fovea
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Rods
- Photoreceptors that become active under low-light conditions for night vision
- Distributed evenly around the retina
- Absent in the fovea
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Receptive Fields
- The region of the sensory surface that, when stimulated, causes a change in the firing rate of a neuron
- Input from an entire patch of adjacent photoreceptors lying side by side in the retina
- The retina is organized to detect edges
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On-Center Cell
Central excitatory zone surrounded by a ring-shaped inhibitory zone
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Off-Center Cell
Central inhibitory zone surrounded by a ring-shaped excitatory zone.
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Visual Processes in the Brain
- Right visual fields of BOTH retinas stimulate the LEFT half of each retina, goes through the thalamus to the left hemisphere
- Opposite for left visual fields
- Area V1 - the part of the occipital lobe that contains the primary visual cortex, specialized for encoding edge orientation (horizontal, vertical or slanted)
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Dorsal Stream
- Occipital lobe to parietal lobe
- Connects brain areas that identify location and motion
- WHERE or HOW
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Ventral Stream
- Occipital lobe to lower levels of the temporal lobes
- Include brain areas that represent shape and identity
- WHAT
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Gestalt Perception
- We perceive a whole object instead of a collection of parts
- Simplicity
- Closure
- Continuity
- Similarity
- Proximity
- Common Fate
- Figure/Ground Distinction
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Simplicity
The visual system tends to select the simplest, most likely interpretation
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Closure
We tend to fill in missing elements to complete a picture (object)
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Continuity
Edges that have the same orientation we tend to group together perceptually
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Similarity
Regions of similar color/shape/texture/lightness we perceive as belonging together
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Proximity
Objects close together tend to be grouped together
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Common Fate
Elements that move together are perceived as part of a single object.
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Figure/Ground Distinction
- Identifying a figure apart from the ground in which it resides
- Size provides a clue as does movement
- Reversible figure-ground relationship
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Monocular Depth Cues
- Aspects of a scene that yield information about depth when viewed with only one eye
- Rely on the relationship between distance and size
- Relative size
- Familiar size
- Linear perspective
- Texture gradient
- Interposition
- Relative height in image
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Relative size
Smaller is father away and larger is closer
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Linear Perspective
Parallel lines converge as they recede into the distance
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Texture Gradient
Arises when viewing a mostly uniformly patterned surface because the size of the patterned elements and the distance between them get smaller as the surface recedes from the observer
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Interposition
One object partly blocks another, and is closer
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Relative Height in Image
Objects closer are lower in the visual field, objects farther away are higher
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Binocular Disparity
- The difference in the retinal images of the two eyes that provides information about depth and gives the world 3 dimensions
- Like the view master
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Consciousness
A person's subjective experience of the world and the mind
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Sleep Stages
- Stage 1: Theta waves, lower than alpha
- Stage 2: Sleep spindles and K complexes, more difficult to awaken
- Stage 3 & 4: Deepest, slow-wave sleep, delta waves
- Stage 5: REM sleep - characterized by rapid eye movements and a high level of brain activity, as active as when awake, dreaming occurs in this stage.
- We cycle through all stage about every 90 minutes when stage 3 & 4 ending halfway through the night.
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Circadian Rhythm
A naturally occurring, 24-hour cycle of rest and activity
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Benefits of Sleep
- Essential for memory consolidation
- Health
- Happiness
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Consequences of Sleep Deprivation
- Learning is not as effective
- Extreme sleep loss can be fatal
- Trouble regulating body temperature and weight
- Reduces mental activity and reaction time
- Increasing irritability and depression, risk of accidents and injury
- Memory problems and excessive aggression with loss of REM sleep
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Insomnia
Difficulty in falling asleep or staying asleep
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Sleep Apnea
A disorder in which the person stops breathing for brief periods while asleep
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Somnambulism
- Sleep walking
- Occurs when the person arises and walks around while asleep
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Narcolepsy
A disorder in which sudden sleep attacks occur in the middle of waking activities
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Sleep paralysis
The experience of waking up unable to move
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Night Terrors
Abrupt awakenings with panic and intense emotional arousal (sleep terrors)
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Psychoanalytic Theory of Dreams
- Dynamic unconscious creates dreams to be confusing and obscure
- Represent wishes, some of which are unacceptable, taboo and anxiety producing that the mind expresses in disguised form
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Activation Synthesis Model
The theory that dreams are produced when the brain attempts to make sense of brain activations that occur randomly during sleep
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Brain Regions Activated When We Dream
- Amygdala
- Visual-association areas
- Motor cortex
- Brain stem
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Brain Regions Deactivated When We Dream
- Prefrontal cortex
- Visual perception areas
- Spinal neurons
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Hypnosis
An altered state of consciousness characterized by suggestibility and the feeling that one's actions are occurring involuntarily, a state of mind
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Meditation
- The practice of intentional contemplation
- A period of quiet
- Alpha waves of relaxation
- Deactivation of the posterosuperior parietal lobe
- An experience of immersion and loss of self
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Developmental Psychology
The study of continuity (things remaining the same) and change (differences and different points in time) across the life span
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Infancy
The stage of development that begins at birth and lasts between 18 and 24 months
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Habituation
- The tendency for organisms to respond less intensely to a stimulus as the frequency of exposure to that stimulus increases
- Change the stimulus a little and babies will show renewed interest
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Infant Perception
- Babies will stare at something in their field of view
- Babies are more attentive to social stimuli and pay more attention to faces
- Babies mimic facial expressions
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Motor Development
The emergency of the ability to execute physical actions such as reaching, grasping, crawling and walking
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Cephalocaudal Rule
The top-to-bottom rule that describes the tendency for motor skills to emerge in sequence from head to feet
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Proximodistal Rule
The inside-to-out rule that describes the tendency for motor skills to emerge in sequence from center to periphery
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4 Stages of Cognitive Development
(Jean Piaget)
- Sensorimotor: Birth to 2 years, experiencing the world through movement and senses, begins to act intentionally, understanding object permanence
- Preoperational: 2-6 years, acquires motor skills, starts by thinking egocentrically but ends with a basic understanding of other minds
- Concrete operational: 6-11 years, can think logically about physical objects and events and understands conservation of physical properties
- Formal Operational: 11+ years, can think logically about abstract propositions and hypotheticals
- Qualifications of this theory: infants demonstrate object permanence earlier than he proposed; transition between stages is not abrupt; children acquire many of the abilities much earlier than suggested
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Assimilation
The process by which infants apply their schemes in novel situations, how objects behave
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Accommodation
The process by which infants revise their schemas in light of new information
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Object Permanence
The idea that objects continue to exist even when they are not visible.
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Conservation
- The notion that the quantitative properties of an object are invariant despite changes in the object's appearance
- Ex: even though eggs are spread out more there is still the same number of eggs; when a ball of clay is rolled, flattened or stretched there is still the same amount of clay
- Children don't understand this in the preoperational stage
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Theory of Mind
The idea that human behavior is guided by mental representations
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3 Fundamental Skills Allowing us to Learn From Others
- Joint attention: The ability to focus on what another person is focused on
- Social referencing: The ability to use another person's reactions as information about the world
- Imitation: The ability to do what another person does, or what they meant to do
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Harry Harlow/Rhesus Monkeys
- No social contact for the first 6 months developed a variety of pathologies
- When the monkey was introduced to others it avoided them
- The monkey was incapable of communicating or learning from others
- Mothers would avoid, reject and sometimes attack their own babies
- Babies put with artificial mothers would cling to the cloth mother over the wire mother that provided food.
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Attachment Styles
- Secure attachment: Calmed by the caregivers presence
- Avoidant: Not distressed when the caregiver leaves and does not acknowledge their return
- Ambivalent: Distressed when the caregiver leaves but rebuffs them when they return and try to soothe, arching and squirming to get away
- Disorganized: No consistent pattern of response to the caregiver
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Internal Working Model of Relationships
A set of beliefs about self, the primary caregiver, and the relationship between them. Different attachment styles have different working models.
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Happiness As Adults
- Married people live longer, have more sex and earn more money
- Children decrease a parents happiness while they are still young.
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Blind Spot
A location in the visual field that produces no sensation on the retina because the corresponding area of the retina contains neither rods nor cones and, therefore, no mechanism to sense light. This is where the optic nerve leaves the eye.
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