Perception and Sensory Neuropsychology
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151 Terms
What is sensation?
The ability to detect some form of stimulation
What is perception?
The act of giving meaning to a detected sensation
Can perception occur without sensation?
Yes
What are the three major scientific approaches used to study sensation and perception?
Thresholds, sensory neuroscience and neuroimaging, and computational models
What question do threshold studies address?
How perceptual abilities can be measured
What question does sensory neuroscience address?
The biological basis of sensation and perception
What question do computational models address?
How mathematical and computational processes can explain perception
Who invented psychophysics?
Gustav Fechner
Why is Fechner considered important in psychology?
He is often regarded as the founder of experimental psychology
What philosophical relationship interested Fechner?
The relationship between mind and matter
What is dualism?
The view that the mind exists separately from the physical body
What is materialism?
The view that only matter exists and that mind and consciousness arise from interactions of matter
What is psychophysics?
The science of defining quantitative relationships between physical stimuli and psychological experiences
What is a two-point threshold?
The minimum distance at which two stimuli can be distinguished as separate
What is a detection threshold?
The minimum amount of stimulation required for a stimulus to be detected 50% of the time
What is a just noticeable difference (JND)?
The smallest detectable difference between two stimuli
What is another name for the JND?
The difference threshold
What is the method of constant stimuli?
A method in which many stimulus intensities are presented one at a time in random order
How is the method of constant stimuli conducted?
Stimuli ranging from rarely detectable to almost always detectable are presented repeatedly
What is plotted on the x-axis in the method of constant stimuli?
Stimulus intensity
What is plotted on the y-axis in the method of constant stimuli?
The percentage of times the stimulus is detected
How does perception typically change with stimulus intensity?
Non-linearly rather than in a sharp linear fashion
What is the method of limits?
A method in which stimulus intensity is gradually increased or decreased until the participant's response changes
How are stimuli presented in the method of limits?
Systematically increasing or decreasing in intensity across trials
How is the threshold estimated in the method of limits?
By averaging the stimulus levels where response changes occur
Can the method of limits begin with high or low intensities?
Yes
What is the method of adjustment?
A threshold measurement method in which the participant directly controls the stimulus intensity
What is discrimination in psychophysics?
The ability to detect differences between stimuli
What did Weber discover about discrimination thresholds?
The JND is a constant proportion of the original stimulus level
What is Weber's Law?
The principle that the JND is a constant fraction of the comparison stimulus
According to Weber's Law, what happens to the JND as stimulus intensity increases?
The JND increases proportionally
According to Weber's Law, what happens to the JND as stimulus intensity decreases?
The JND becomes smaller
What does the Weber-Fechner Law describe?
The relationship between physical stimulus intensity and perceived differences
Why does the required difference between stimuli increase at higher intensities?
Because the JND scales with the magnitude of the original stimulus
According to the Weber-Fechner example, how much must a 1 kg weight change to be noticed?
Approximately 0.1 kg
According to the Weber-Fechner example, how much must a 100 kg weight change to be noticed?
Approximately 10 kg
What is the black box problem in psychophysics?
The difficulty of observing the internal brain processes that connect stimuli to perception
What can psychophysicists directly measure?
Physical stimuli and subjective responses
What cannot be directly observed in the black box problem?
The internal neural mechanisms that produce perception
What is sensory neuroscience?
The study of the biological basis of perception
How are cortical areas organised according to sensory neuroscience?
Different areas are specialised for different sensory and motor functions
What is neuronal firing?
The generation of action potentials by neurons
What is an action potential?
An electrical signal that travels along a neuron
How do neurons fire action potentials?
In an all-or-none fashion
What indicates how excited a neuron is?
The number of action potentials fired per second
Where does an action potential begin?
Near the neuron's cell body
In which direction does an action potential travel?
Down the axon toward the axon terminals
Which ions are primarily involved in action potentials?
Sodium (Na+) and potassium (K+) ions
How is information processed in the nervous system?
Through coordinated activity across populations of neurons
Why is neuronal firing alone insufficient to explain perception?
It is not always clear where or when conscious perception occurs
What can studies of neuronal firing reveal?
Functional networks, connectivity, and neural selectivity
What is electroencephalography (EEG)?
A technique that measures electrical activity from large populations of neurons using electrodes placed on the scalp
What does EEG measure?
Electrical activity generated by populations of neurons
What is an event-related potential (ERP)?
A measure of electrical activity in response to specific stimuli derived from averaged EEG recordings
How are ERPs obtained?
By averaging multiple EEG responses to the same stimulus
What is magnetic resonance imaging (MRI)?
An imaging technique that uses strong magnetic fields to create images of body structures, including the brain
What does MRI primarily measure?
Brain structure
What is functional magnetic resonance imaging (fMRI)?
A technique that measures brain activity by detecting changes in blood oxygenation
What does the BOLD signal stand for?
Blood oxygen level-dependent signal
What does the BOLD signal measure?
The ratio of oxygenated to deoxygenated haemoglobin
Why is the BOLD signal useful?
It helps identify brain regions involved in specific tasks
Why are EEG and MRI/fMRI often combined?
Because they complement each other's strengths and weaknesses
What can EEG and MRI/fMRI help scientists understand?
The biological processes that support sensation and perception
What are computational models?
Mathematical or computer-based simulations of psychological or neural processes
Why are computational models useful?
They simulate how perception and cognition may operate
What are efficient coding models?
Models proposing that sensory systems efficiently encode predictable information in the environment
What is the goal of efficient coding models?
To represent sensory information as efficiently as possible
What are Bayesian models?
Models that use prior knowledge and probability to make predictions about sensory input
What principle underlies Bayesian models?
Bayesian statistics and prior expectations
What are artificial neural networks?
Computer systems that simulate interconnected biological neurons
How do artificial neural networks process information?
Through interconnected layers of units that can excite or inhibit one another
What are deep neural networks (DNNs)?
Artificial neural networks with multiple layers that are effective at classifying large amounts of information
What are DNNs particularly good at?
Classifying information into categories
How are DNNs relevant to perception research?
They can partially predict human perceptual processes