Sensation, Perception, and Consciousness Flashcards
What is sensation?
The detection of physical energy by our sensory organs, which is then relayed to the brain
What organs are associated with which senses?
- Light waves (eyes)
- Sound waves (ears)
- Pressure (skin)
- Chemicals (tongue)
- Air born chemicals (nose)
What is perception?
The process of attending to, organizing, and interpreting the raw sensory input from the sensory organs, how psychology starts to play in
How do we make sense of the world?
- Bottom-up processing: taking sensory information and then assembling and integrating it (what are you seeing?)
- Top-down processing: using models, ideas, and expectations/schemas, to interpret sensory information (is that something you have seen before?)
How do the sensory organs communicate to the brain?
- Reception: the stimulation of sensory receptor cells by energy (sound, light, heat, etc.)
- Transduction: transforming this cell stimulation into neural impulses
- Transmission: delivering this neural information to the brain to be processed
What is absolute threshold?
The minimum level of stimulus intensity needed to detect a stimulus half the time
What is subliminal?
Below our threshold for being able to consciously detect a stimulus, but still registered by the sensory organ
What is difference threshold?
Refers to the minimum difference for a person to be able to detect the difference half the time
What is Weber’s law?
For two stimuli to be perceived as different they must differ by a constant minimum percentage (proportion) and not a constant amount ♣ Light = 8% ♣ Weight = 2% ♣ Tone = 3% ♣ Pitch = 0.3%
What is the signal detection theory?
Aims to explain whether or not we detect a stimulus, particularly with background noise
- Suggests that detection depends on psychological factors such as alertness, expectations, motivation, as well as sensory experience (not just receptors)
- Thus, detection is impacted by both sensation (bottom up) and perception (top-down)
What is Gestalt psychology?
Tries to understand the laws of our ability to acquire and maintain meaningful perceptions in an apparently chaotic world
What is the law of Pragnanz?
We perceive stimuli in our environment in their simplest form
- Proximity: objects physically close to each other tend to be perceived as unified wholes
- Similarity: objects similar to each other tend to be perceived as unified wholes
- Continuity: we still perceive objects as wholes even if others block part of them
- Closure: parts are combined to create wholes
- Symmetry: we perceive objects that are symmetrically arranged as wholes
- Figure-ground: figure is the centre of our attention, we ignore the background
What are energy waves to our eye?
Wavelength: becomes colour, or hue
Amplitude: becomes intensity, or brightness
How does vision work?
- Light entering eye triggers photochemical reaction in rods and cones at back of retina
- Chemical reaction in turn activates bipolar cells
- Bipolar cells then activate ganglion cells, the axons of which converge to form the optic nerve
- Some ganglion cells are dedicated (visual patterns, certain edges, lines, movement)
- Supercells integrate these feature signals to recognize more complex forms (faces, Jennifer Aniston cells)
- This nerve transmits information to visual cortex (thalamus) in the brain
What is the Young-Helmholtz Trichromatic Theory?
Assumes 3 types of colour receptors/cones (red, green, blue), anything else is a combination of these 3
- Bees also have trichromatic vision, except see colours more to the purple end of things
- Dogs have dichromatic vision (blue and green/yellow)
What is the Ishihara test?
Genetic disorder that prevents people to perceive certain colours like red and green (colour-blind)
Observations which support the trichromatic theory
What is the opponent-process theory? What is one example?
Neural process based on sets of complementary colours
- White/black, yellow/blue, red/green
- Pairs inhibit each other
- Eg. normally if white is coming in the eyes, red and green will fire at the same time
- But if red has just been stimulated, it is tired, and only green fires
- So, the brain thinks it’s seeing a green dot, when in fact the eye is presented with white
Which colour theories are supported?
- Both colour theories are supported
- Young-Helmholtz Trichromatic Theory works at the receptor level (cone)
- Opponent process theory works in ganglion cells in the eye as well as the visual cortex
- Another example of how sensation (eg. types of cones) and perception (eg. visual cortex) have to interact to create our experience of a whole
What are the cues that give our brain information about depth?
Monocular cues, and binocular cues
What are monocular cues?
Cues that only require one eye, which we use to perceive depth
What are the types of monocular cues?
- Linear perspective: lines converge to a common point at a distance
- Relative size: more distant objects look smaller
- Texture gradient: texture of objects become less apparent the further they are
- Interposition: closer objects block our view of objects further away
- Height in plane: in a scene, distant objects are higher and closer objects are lower
What are the types of binocular cues?
- Binocular disparity: each eye transmits different information for near object, but they become similar the further away objects are
- Binocular convergence: when we look at nearby objects our eyes converge together
- Brain can track eye muscle movements and use that information to estimate distance
- Eg. if muscles are activated in that cross-eyed fashion then it is closer to you
What is the doctrine of specific nerve energies?
Different senses are separated in brain
What is the orientating response?
Describes how quickly we shift our attention to stimuli that signal a change in our sensory world
What is sensory adaption?
Reduction of activity in sensory receptors with repeated exposure to stimulus
What are the 4 possibilities when judging someone’s sensory ability?
- Hit: yes you heard something
- Correct rejection: yes you didn’t hear something
- False alarm: no you didn’t hear something
- Miss: no you didn’t hear something
What is divided attention? What is selective attention?
- Divided attention: we are paying attention to more than one stimulus/task at a time
- Selective attention: focusing on a particular event or task
What is inattentional blidnness?
Failure to notice clearly visible events or objects because attention is directed elsewhere
What is myopia? What is hyperopia?
Myopia/nearsightedness: prevent focused image from reaching photoreceptors in retina
Hyperopia/farsightedness: see distant objects clearly but not those close by
What are the structural components of the eye?
- Sclera: white outer surface of eye
- Cornea: clear layer that covers front portion of eye and contributes to eye’s ability to focus
- Pupil: regulates amount of light that enters by changing size called accommodation (diliates to allow more light to enter)
- Iris: round muscle that adjusts pupil size, gives eyes colour
- Lens: clear structure that focuses light behind pupil
- Retina: lines inner surface of eye and consists of specialized receptors that absorb light and send signals related to properties of light to brain
- Ganglion cells: gather information from photoreceptors and sent through optic nerve (dense bundle of fibres that connect to brain)
- Optic disk: area with no photoreceptors where nerves reside (blind spots)
What can be found in the retina?
- Photoreceptors: light transformed to neural signal that brain can interpret, back of eye to protect it and provided with blood
- Rods: photoreceptors that occupy peripheral regions of retina, highly sensitive under low light levels (black, grey)
- Cones: photoreceptors that are sensitive to different wavelengths of light, tend to be clustered around fovea (center of retina)
How does light reach the eye?
- Light enters eye through cornea and passes through pupil
- When light reaches back of eye, will stimulate layer of specialized receptors in retina that convert light into message that brain can interpret (transduction)
- When rods and cones are stimulated, physical structure changes to decrease glutamate neurotransmitter released which alters neuron activity
How does information from the eye reach the brain?
- Information from optic nerve travels to optic chaism (where optic nerves cross midline of brain) from the same side (ipsilateral) or opposite side (contralateral)
- Right half of visual field is initially processed by left hemisphere and vice versa
- Fibres from optic nerve connect with thalamus
- Lateral geniculae nucleus: processes visual information, send messages to visual cortex (occipital lobe)
- Primary visual cortex uses feature detection cells which respond selectively to simple and specific aspects of stimulus (angles, edges)
- Secondary visual cortex receives information about difference features and further processes
What are the components (streams) of the secondary visual cortex?
- Ventral steam (visual cortex to temporal lobe): object recognition
- Groups of neurons in temporal lobe gather shape/colour from secondary visual cortex and combine into object
- Perceptual constant: the ability to perceive objects as having constant shape, size, colour despite changes in perspective
• Shape constancy: judge angle relative to our position
• Colour constancy: recognize colour under various levels of illumination
• Size constancy: judgements of how close object is relative to one’s position and other objects’ positions - Dorsal stream (visual cortex to parietal lobe): locates object in space and allows you to interact with it
What is parallel processing?
Building perceptions out of sensory details processed in different areas of the brain at the same time
What is bottom up processing?
Construct the whole from its parts, starts with activity in the primary visual cortex followed by the association cortex
What is top down processing?
Starts with our beliefs and expectations, which we impose on the raw stimuli captured by our senses, starts with activity in the association cortex followed by the primary visual cortex
What is consciousness?
Refers to a person’s subjective awareness of internal and external stimuli, including thoughts, perceptions, experiences, and self-awareness
What are the characteristics of steams of consciousness?
- Every thought tends to be a part of a personal consciousness
- Consciousness is in constant change (trying to stop thinking about something morphs into you thinking about trying to stop)
- With each personal consciousness thought is sensibly continuous (there is a flow that comes with your stream of consciousness)
- It attends to some stimuli but excludes others
What is attention?
Perception involves processing sensory information in such a way that it produces conscious experiences that we attend to
What is Broadbent’s filter theory of attention?
- Attention is bottleneck through which information passes
- Filter allows us to pay attention to important stimuli while we ignore others
What is selective and inselective attention?
Selective attention: what we focus on is what we consciously perceive
- Attention shapes how we construct the world around us
- It is a limited ability because attention is removed from another if you focus on one stimuli
Selective inattention: refers to our failure to notice parts of our environment when our attention is directed elsewhere
What is subliminal levels? Does it work in marketing?
- Below our threshold for being reliably able to consciously detect a stimulus but still registered by the sensory organ (below conscious detection, stimuli are picked up by sensory organs but you won’t be aware)
This type of marketing can work in certain conditions for a short period of time (in a lab without any other distraction) but in real life there are too many distractions, you’re not putting attention on it
You can accentuate tendencies that someone already has but won’t act in ways they won’t
What is naive realism?
- False belief that our senses are infallible and that our perceptions offer perfect representation of the world
- In reality, the sensory organs are not as good as we feel they are, and the brain fills in a lot of information to create our experience of reality
What is the unconscious low track?
- Bottom up
- Below the absolute threshold, yet still registered by sensory organ
- Does not require attention
- Often leads to automatic actions based on cues that our sensory organs capture
- Eg. helps you socially, smiling back at someone who smiles at you automatically
What is the conscious high track?
- Top down
- Above the absolute threshold
- Requires attention, effort
- Often leads to deliberate actions based on what we recognize in our environment (less contribution to consciousness)
What is the binding problem? What is a recent theory?
- How we combine pieces of low and high track together to create a unified whole
- Eg. seeing form, colour, motion, and depth into a video of a bird
- Recent models are from perspective of iteration processing
- Areas process information very rapidly and in coordination with each other
- Repeat the process as needed
- Initial iterations provide relatively quick perceptions
- Inform whether additional iterations are needed and what type of processing is required
- Additional iterations accompanied by reflective processes (conscious high track) yield more nuanced perceptions
What are context effects?
- Context provides us a basis for expectations
- Eg. if you see dentist at a heavy metal concert, you will probably not recognize them because you know them at a certain way
- Eg. grammar which has been mastered; if every other letter of a sentence has been replaced can still be read because of past experience with the English language
What is perceptual sets?
What we expect to see influences what we do see (top-down processing)
What is perceptual constancy and the types?
Perceptual constancy: ability to perceive objects as having constant shape, size, and colour despite changes in perspective (acquired due to experience, top down processing)
- Shape constancy
- Size constancy
- Colour constancy
