Sensation and Perception Flashcards
bottom up processing
environment or sensory information processing
top down processing
information from own knowledge processing
serial processing
processes one thing at a time
parallel processing
processes many different things at the same time
sensation
registering stimulation of the senses
perception
processing and interpreting sensory information
cognition
using perceived information to learn, classify and comprehend
bottom up perception
perception starts with the physical characteristics of stimuli and basic sensory processes
Gibson - ‘direct perception’
top down perception
we perceive concepts of our understanding of external stimuli based on past experience and knowledge
Gregory
Gibson direct perception
info coming from sensory receptors is enough for perception to be rich and detailed
complex mechanisms not necessary
environment contains sufficient cues to provide context to aid perception
e.g. texture - depth
Perception starts with one of the following ‘changes’
- electromagnetic energy (light/vision)
- chemical composition (taste)
- chemical composition (smell)
- air pressure waves (sound)
- tissue distortion (touch)
- gravity and acceleration
perception of changes is detected by different types of receptors
vision - photoreceptors
taste - chemoreceptors
smell - chemoreceptors
sound - mechanoreceptors
touch - mechanoreceptors and thermoreceptors
gravity and acceleration - mechanoreceptors
the info detected by receptors then passed on via different pathways
vision - photoreceptors - primary visual cortex
taste - chemoreceptors - gustatory cortex
smell - chemoreceptors - olfactory cortex
sound - mechanoreceptors - auditory cortex
touch - mechanoreceptors and thermoreceptors - somatosensory cortex
gravity and acceleration - mechanoreceptors - temporal cortex
sensation to brain pathway
environmental stimulus >
receptors >
intermediate neurons >
thalamus*: neuron mass in middle of brain >
receiving area in cortex >
secondary (associative) cortex >
higher cortex
Transduction
conversion of environmental energy into nerve signals
Feedback
- feedback projections from different parts of the brain towards the more sensory parts of the brain
- help modulate our experience
- keep some of our experiences more stable
Gregory
perception is not simply determined by stimulus patterns
it is a dynamic searching for the best interpretation of the available data
Ways to investigate perception and sensation
- staining
- single-cell recordings (electrophysiology)
- fMRI
- Lesion studies
- ERP from EEG
- optical imaging/near infra-red spectroscopy (NIRS)
- psychophysics
- illusions and introspection
- computational modelling
- single-cell recording
single-cell recording
- action potentials of neurons are recorded with microelectrodes inserted close to cell
- requires section of skull to be removed
- useful for identifying cells which are selective for certain features
virtual lesions - TMS
- pulses of magnetic energy disrupt activity in a small part of the brain for a short period
psychophysics
quantifying the relationship between physical stimuli and the psychological response
absolute/detection threshold vs difference threshold
absolute/detection threshold
smallest stimulus needed for detection
e.g., min concentration of flavour you can taste
difference threshold
smallest difference between two stimuli that can be detected - the ‘just-noticeable difference (JND)’
e.g. the min diff between 2 colours that you can see
global form task
which quadrant has a shape in it
biological motion task
videos of dots moving - does it or does it not look like a person walking
autistic children find this harder
