Week 1 Flashcards
Basic steps for sensation and perception
Detection of environmental stimulus –> transduction –> Processing –> Perception (meaning/significance) –> recognition –> action
Repeats –> sensitisation or adaptation over time.
When you sense danger
- An object
- See/hear: eyes, ears –> stimulus ( light/soundwaves) activates receptors
- Receptors –> convert the stimulation to electrical signals
- E/S –> Ascending pathways –> the thalamus
- Sensory cortex __> identify characteristics –> access the library (memory)
- Identify the object –> perceive/recognize (ex: fear)
- Response/action
Modalities of senses/basic mechanisms
Vision - light
Audition- sound
Olfaction - chemical
Touch - pressure
Taste - chemical
Pressure - baro sense
Temp - thermo sense
Osmolarity - Oslo sense
Humidity - hydro sense
Sensation “definition”
Detection of stimulus
Transduction
Delivery of signal to the brain
Perception “definition”
Conscious experience of the stimulus
Translation of delivered signal
Identifying the stimulus (recognition)
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Perceptual process 1-7
1-2: Stimulus:
3: Detection by receptor
4: Neural Processing
5-6: Perception <–> Recognition
7: Action
- 1-7 steps happen continuously and repeatedly
–> Adjusts threshold in sensation
–> Refines perception (perceptual processes) - Perceptual process updates the knowledge (library) and knowledge influences perceptual processes (bottom-up vs top-down process)
Environment/external information
Stimulus from outside the body
Visceral information
Stimulus from inside the body
1-2: Stimulus:
- From outside of the body (environment / external information)
- From inside of the body (visceral information)
- Physical element/property
- Light, chemical, soundwave etc..
- Brain has no idea what it is
3: Detection by receptor
- By modality
- Receptor as transducer
- Detection of corresponding physical stimulus (light, pressure, sound waves, chemicals)
- Generation of electrical signals
- Delivery of signals to the CNS
4: Neural processing
- Conveys electrical signals using action potentials
- Ascending pathways via the spinal cords to the brain
- First to the thalamus (sensory thalamus) – gate keeper
- Sensory gating
5-6: perception <–> recognition
- If passed the gate at the thalamus, then to the sensory cortex
- Perception begins
- Reaches the stage of the consciousness
- Analysis of element
- Compare the stimulus to references (memory) –> identification of the stimulus (recognition)
7: Action
- By sending information to other relevant brain areas
- Motor response
- Emotional response
- Other cognitive actions
- Physiological actions
- Etc…
Environment <–> Sensation and perception
(Contrast effect and adaptation effect)
A dark scene might be perceived darker when seen just after being in the light.
The scene would be perceived lighter after having spent 10-15 minutes adapting to the dark.
The improvement in perception after spending some time in the dark reflects a decrease in the threshold for seeing light.
Perceptual disorders
- Agnosia:
- An inability to recognise or identify the objects, people, shape, smell, etc due to the deficits in sensory information processing.
- Modality specific - Can not be explained by problems in other cognitive functions (memory, language, unfamiliarity, etc)
- Visual agnosia
- An inability to name or describe the use for a visual object
- Ex: a rose –> a convoluted red form with a linear green attachment
- Still be able to reach for it and pick it up
- Can also touch to identify what it is or its use once you’re holding it.
- No difficulty in detecting motion, interpreting location information
- Problem with the ventral visual pathway - Nothing wrong with memory –> perceptual problem
- Auditory agnosia
- Tactile agnosia
- Olfactory agnosia
- Gustatory agnosia
