Chapter 5: Sensation and Perception Flashcards
Sensation
- The detection of physical energy emitted or reflected by physical objects.
- Occurs when energy in the external environment or the body stimulates receptors in the sense of organs.
Perception
Process by which the brain organizes and interprets sensory information.
What are separate sensations?
- Specialized cells that convert physical energy in the environment or the body to electrical energy that can be transmitted as nerve impulses to the brain.
- Dendrites of sensory neuron’s responsible for smell, pressure, pain, and temperature.
- Specialized cells for vision, hearing, taste
What is synthesia?
Sensory crossover from one modality to another can sometimes occur
In synthesia, sensation in one modality consistently evokes a sensation in another.
A person with synthesia may say things like:
The colour purple smells like a rose
The aroma of cinnamon feels like velvet
The sound of a note on a clarinet tastes like cherries
- The neurological basis of synesthesia is uncertain.
Psychophysics
Filed concerned with how the physical properties of stimuli are related to our psychological experience of them.
Commonly relies on measuring absolute threshold, difference threshold, and applying signal-detection theory.
Absolute Threshold
The smallest quantity of physical energy that can be reliably detected by an observer (50% of the time).
Senses are sharp, but only turned into narrow band of physical energies.
EX. When it goes from nothing, to something. Ex. volume from 0 to 1
Difference Threshold
The smallest difference in stimulation that can reliably be detected by an observer when two stimuli are compared.
Also called just noticeable difference (JND)
Ex. volume between 19 and 20
Weber’s Law
When it’s harder to tell the difference between volume at 30 and 35 than it is between 5 and 10.
Signal Detection Theory
Divides the detection of sensory signals into a sensory process and a decision process.
Sensory Adaptation
Reduction or disappearance of sensory responsiveness when stimulations is unchanging or repetition (habituation).
Useful as it spares us from responding to unimportant information.
Ex. Swimming, night vision, adapting to senses like food, smelly room
Sensory Deprivation
Focusing of attention on selected aspects of the environment and blocking out the others.
Useful skill for young children who are in classrooms (e.g., working in groups blocking out noise from other classrooms, children)
Inattentional Blindness
Failure to consciously perceive something you are looking at because you are not attending to it.
Ex. Opening the fridge and looking right at something and not seeing it.
Vision
Light stimuli (waves) have physical characteristics that affect three psychological dimensions of our visual world: Hue, Brightness, Saturation
Hue
Dimension of visual experience specified by colour names.
- Related to the wavelength of light.
Brightness
Dimension of visual experience related to the amount of light emitted from or reflected by an object.
- Related to amplitude of wavelength.
Saturation
Dimension of visual experience related to the complexity of light waves.
- Vividness or purity of colour.
Feature Detector Cells
Cells in the visual cortex that are sensitive to specific features of the environment (faces, shapes).
Trichromatic Theory
Proposes that three types of cones are sensitive to a certain range of wavelength (red, blue, green) (RBG. These are the values that produce different colours).
- Interaction in three cones produces the different experience of hue.
Colour Blindness
typically a generic variation causing the absence or dysfunction of one or more of the cones.
Most are “colour deficient” meaning the person is unable to distinguish red and green (see everything as blue, yellow, brown, and grey).
Opponent-Process Theory
Assumes that the visual system treats pairs of colours as opposing or antagonistic.
Occurs in the ganglion cells, and neurons in the thalamus and visual cortex.
Three opponent pairs: red/green; blue/yellow; black/white
Cells that are inhibited by one colour, produce burst of firing when opponent colour presented.
Negative Afterimage
Occurs when you see the inverse colour of the original photograph. An example of this is when you stare at a red image for a period of time and when you look away you should see a green afterimage.
What are the Gestalt principles?
Proximity: things near each other tend to be grouped together.
Closure: the brain fills in gaps to perceive complete forms.
Similarity: things that are alike are perceived together
Continuity: lines and patterns tend to be perceived as continuing in time or space
Perceptual Constancy
The accurate perception of objects as stable or unchanged despite changes in the sensory patterns they produce.
- Best-studied are shape, location, size, brightness, and colour constancies.
Binocular cues
Used for objects that are fairly close to us.
Our eyes converge (turn inward) when we focus on an object that is close to us.
Monocular cues
Used when objects are far away.
Monocular cues are visual cues to depth or distance that can be used by one eye.
Perceptual Illusions
give us information about perceptual strategies used by brain, and how misleading messages are interrupted.
Sound Localization
relies on loudness and intensity of stimuli to tell us where a sound is coming from.
5 Main Tastes (Gustation)
salty, sour, bitter, sweet, umami (pleasant savoury taste - breastmilk, tomatoes, fish).
Supertasters
Individuals who have more taste buds, and smalled papilla.
- Find some foods unpleasantly bitter.
Smell (Olfaction)
Smell is important in detecting danger (smoke, food spoilage, gas leak, etc.).
Sense of smell sometimes lost through infection, disease, injury, or smoking.
Smokers (2 packs/day) must abstain 10 years for smell to return to normal.
Psychological effects of smell include evoking memories and emotions but may also include evoking behaviours.
Basic skin senses?
Touch (pressure), warmth, cold, pain.
Certain spots on skin especially sensitive to 4 basic sensations.
How does pain differ from other skin senses?
When stimulus producing pain is removed, the sensation may continue (e.g., chronic pain)
Very cold toes - sense pain when toes are warming up to room temperature
Gate-control theory of pain
The experience of pain depends in part on whether pain impulses get past a neurological “gate” in the spinal cord and reach the brain (2min 32sec mark).
Neuromatrix theory of pain
- Matrix of neurons in the brain is capable of generating pain (& other sensations) in the absence of signals from sensory nerves.
- Accounts for phantom pain.
- 38 minute mark
Kinethesis
Sense of body position and movement of body parts (also called kinesthesia).
Equilibrium
Sense of balance.
- Influenced by semicircular canals: sense organs in the inner ear that contribute to equilibrium by responding to rotation of the head.
Inborn abilities
Infants born with basic sensory abilities which rapidly develop.
What other ways is perception influenced
Needs: more likely to perceive something when we need or have an interest in it.
Beliefs: What we believe and can affect what we perceive.
Emotions: can influence interpretations of sensory information (especially pain and fear)
Expectations: previous experiences influence what we perceive (e.g., perceptual set).
How does perception differ through culture?
- Different cultures provide different environments and levels of practive.
- Muller-Lyer illusion not effective in “less-carpentered” cultures.
- Western cultures focus more on figure than ground; East Asian cultures focus more on context.
