Lecture 3 Flashcards
The Three Steps of Sensation and Perception
- Tranduction
- Transmission
- Perception
Transduction
The physical stimulus interacts with a specific receptor location on a peripheral sensory neuron and causes the neuron to fire (causes an action potential)
-The stimulus is transduced into a electrical signal
Action Potential
A rapid, temporary electrical signal that travels along the membrane of a neuron or muscle cell. It occurs when the cell’s membrane potential rapidly depolarizes and then repolarizes, allowing the cell to transmit information or trigger a response.
Transmission
-The synapse (how signals are transferred from neuron to neuron)
-Cranial nerves (neural signal enters CNS)
-Somatic nerves (sensory signals enter spinal cord)
-Thalamus (RELAY station, increase or decrease the input from sensory neurons)
Perception
-Through sensory corticles (in the brain)
Stanley Smith Stevens
-In proportion, how much more/less intense are 2 stimuli of different intensities perceived?
-psy(I) = kl^a
-tweaked Frechner’s formula to allow exponential shape
Stanley Smith Stevens psy(I) = kl^a
psy = subjective percept
I = stimulus intensity
a = controls the curvature of the function
k = corrects for the scaling of measurements units used for I
Absolute Magnitude Ratings
How intense is a percept in relation with two ‘‘absolute’’ boundries?
- E.g. 0= no pain to 100 = worst pain imaginable
-Problem = is my 10/100 equal to your 10/100
-Solution = cross-modality matching (gLMS Scale)
Prothetic Sensations
Sensory experiences that vary in intensity or magnitude, such as loudness, brightness, or weight. They are often measured on a continuous scale + are additive in nature.
-E.g. Quantity of pain intensity?
Metathetic Sensations
These are sensory experiences that vary in quality or kind, such as changes in pitch, colour, or taste. They involve categorial or qualitative changes rather than variations in intensity.
-E.g. Quality of pain. Burning? Stinging? Throbbing?
Detection Threshold
The minimum intensity of a stimulus required for a person to perceive its presence
Threshold is Probabilistic
The difference in stimulus intensity for which a difference is expected to be perceived 50% of the time
Thresholding : Methods of Constant Stimuli
An experimental technique that is used to measure a participant’s perceptual ability in a given task. This method involves presenting stimuli of varying intensities or levels to participants and then measuring their responses to the stimuli.
-Stimuli randomly picked
Thresholding : Methods of limits
A stimulus is presented and increased or decreased until it is perceivable by the subject.
Thresholding : Staircase Method
A variable stimulus is presented repeatedly and is adjusted upwards whenever it is not perceived and downwards whenever it is perceived.
-Get the response -> reverse it
Thresholding : Method of Adjustment
The participant adjusts a variable stimulus to match a constant or standard. For example, the observer is shown a standard visual stimulus of a specific intensity and is asked to adjust a comparison stimulus to match the brightness of the standard
Signal Detection Theory
Seperates your capability of detecting a stimulus from your decision to percieve a stimulus
Signal
The true sensory information coming from the external world
Noise
The various physiological or psychological processes influencing our perception of that external stimulus in an unpredictable manner.
-Can boost your perception or decrease it
Response Bias
- People that are more conservative/withhold correct identifications until it is completely clear / higher thresholds/ interpreted as lower sensory sensitivity
- People that are more liberal / quick to say that they perceived something / lower thresholds/ wrongfully detect the presence of a sensory stimulus when there is none
Sensitivity (d’)
In signal detection theory (SDT), refers to an individual’s ability to distinguish between signal and noise, reflecting how well they can detect a target stimulus.
-Higher sensitivity indicates better discrimmination
Criterion
The decision threshold set by an individual in SDT, determining whether they report the presence of a signal. It reflects their response bias, influenced by factors like expectations or consequences of false alarms and misses.
-Their own set cues
