Introduction to sensation and perception Flashcards
What is the goal of sensation and perception?
To find out about the external world
What is sensation?
the starting point – receiving information about the world via our senses
- Sensory receptor cells are sensitive to physical properties of the world
What are receptor cells?
specialised neurones which respond to a particular physical properties of environmental stimuli
What is perception?
the end point - our experience of the world
Why should we study perception?
- Perception underlies all our interactions with the environment
- Perception allows survival
- Practical applications:
Understand changes in ageing, disease, injury etc.
Demands of driving, interacting with technology etc.
Design of artificial perceptual systems
What is the perceptual process?
- distal stimulus
- proximal stimulus
- receptor processes
- neural processing
- perception
- recognition
- action
- knowledge
What is the distal stimulus?
Physical object in the environment
What is the proximal stimulus?
- The proximal stimulus is a representation of the distal stimulus
- Each sense receives information about the distal stimulus via a different type of environmental physical energy (smell and taste – chemical concentration) (hearing – sound waves)
What happens with the receptor processes?
Receptor cells carry out transduction
What is transduction and give examples with light and hearing?
the transformation of environmental physical energy into electrical energy in the nervous system
- Vision – receptors in the retina transform light into electrical impulses
- Audition – receptors in the inner ear transform sound into electrical impulses
What is neural processing?
- Electrical signals are transmitted from one neuron to the next
- The signal is changed as neurons interact
What is perception, recognition and action?
- Perception – conscious sensory experience (e.g. hear your phone vibrate)
- Recognition – placing an object in a category (e.g. recognise it is your phone)
- Action – movement: eyes, head, body (e.g. look at your phone)
- Action, recognition, and perception all influence each-other
What do stage of the perceptual processes do reflexes bypass?
the recognition stage
How does knowledge influence perception?
- Existing knowledge, assumptions, memories can influence perception, recognition and action
- The effect of knowledge is referred to as ‘top down processing’
What is bottom up and top down processing?
- Bottom-up processing – processing based on incoming sensory information
- Top-down processing – processing based on prior knowledge/ experience/ assumptions
What types of processing does perception involve?
Both bottom-up and top-down
What is top-down processing important for?
helping to simplify the very complex perceptual process
What are the two approaches to the study of perception?
- Physiological – what’s going on in the brain?
2. Psychophysical – what do we perceive?
What are four different methods in the physiological approach of studying perception?
- studying anatomy
- recording brain activity
- microstimulation
- lesioning and TMS
What does studying anatomy involve?
staining cells, sections of the visual cortex
How can you record brain activity?
- Single cell recording
- Imaging
fMRI
MEG
EEG
PET
What is microstimulation?
When you insert two electrodes into the brain – one stimulates the electrical activity and the other record the activity
What is lesioning and TMS?
- Lesioning – brain damage introduced to brain of animal and effect of damage observed
- TMS: magnetic field produces temporary lesion on brain – used in humans
What does the psychophysical approach do?
- Study what people actually perceive
* Measures the relationship between the stimulus (physical world) and perception (psychological world)
What thresholds can psychophysics measure?
- Absolute (detection) threshold – what is the smallest magnitude that we can perceive (e.g. what is the smallest amount of light we can see)
- Difference(discrimination) threshold – what is the smallest difference that we can perceive? (e.g. holding a weight in either hand – what is the smallest difference in weight you need to know that they are different?)
What do the results of psychophysics highlight?
the relationship between physical world and perceptual experience
