What is perception?
Perception is our experience of sensation, involving the brain’s interpretation of sensory information received from the environment.
What are the human senses?
The main senses include touch, smell, sight, hearing, and taste, along with proprioception (body position), nociception (pain), thermoreception (temperature), balance, and body movement.
What is the perceptual process?
The perceptual process follows: Distal stimulus → Proximal stimulus → Conversion into neural signals → Signal processing in the brain to form perception.
What is psychophysics?
Psychophysics is the science that defines quantitative relationships between physical stimuli and the subjective psychological experiences they produce.
What is the absolute threshold?
The absolute threshold is the minimum amount of stimulation necessary for a person to detect a stimulus 50% of the time.
What is the method of adjustment?
In this ‘quick and dirty’ method, participants adjust a dial or button until they can perceive the stimulus. It’s fast but less precise.
What is the method of constant stimuli?
A set of predetermined stimuli spanning a likely range of thresholds are presented, and the participant indicates yes/no responses across trials to determine detection rate.
What is the staircase method?
A method that adjusts stimulus intensity one step up or down depending on the participant’s response, providing a more accurate estimate of threshold than the method of adjustment.
What is the difference threshold (JND)?
The difference threshold, or Just Noticeable Difference (JND), is the smallest detectable difference between two stimuli, measured using methods like adjustment or constant stimuli.
What is psychophysical scaling?
Psychophysical scaling examines how the difference threshold depends on the magnitude of the stimulus, showing that perception changes relative to stimulus size (e.g., Weber’s Law).
Who was Ernst Weber?
Ernst Weber (1795–1878) discovered that the smallest detectable change in a stimulus is a constant proportion of the original stimulus, forming the basis of Weber’s Law.
Psychophysical scaling
What is Weber’s Law?
Weber’s Law (JND = kI) states that the Just Noticeable Difference is a constant fraction (k) of the stimulus intensity (I), meaning perception depends on proportional rather than absolute changes.
What is Fechner’s Law?
Fechner’s Law (S = k ln(I/I₀)) relates perceived intensity (S) to the logarithm of the ratio between a stimulus’s physical intensity (I) and the threshold intensity (I₀). It works well for brightness and loudness but not all sensations.
What is Stevens’ Law?
Stevens’ Law (S = cIⁿ) states that perceived intensity (S) varies according to stimulus intensity (I) raised to an exponent (n), which differs for each sensory dimension (e.g., brightness vs. pain).
Who was Johannes Müller?
Johannes Müller (1801–1858) proposed the doctrine of specific nerve energies, asserting that the nature of a sensation depends on which neurons are active, not how they are stimulated.
Who was Charles Sherrington?
Charles Sherrington (1857–1952) discovered that neurons are not physically connected but communicate through networks, forming the foundation of modern neuroscience.
Who was Wilder Penfield?
Wilder Penfield (1891–1976) found that stimulating certain brain regions could evoke sensations like touch in specific parts of the body, mapping sensory regions of the cortex.
Who was Horace Barlow?
Horace Barlow (1921–2020) formulated the neuron doctrine (1972), emphasizing that perception arises from the activity of specialized neurons each selective for specific stimulus features.
Who was Santiago Ramón y Cajal?
Santiago Ramón y Cajal (1852–1934) produced detailed neuron drawings, discovered synapses, and won the Nobel Prize for revealing the neuron as the fundamental unit of the nervous system.
What are neurons?
Neurons generate and transmit electrical signals in the brain, allowing for communication between sensory inputs and cognitive processing.
What is the typical resting potential of a neuron?
The resting potential is about -70 mV, maintained by high intracellular K⁺ and low Na⁺, with the membrane most permeable to K⁺ at rest.
What generates an action potential?
An action potential occurs when voltage-gated sodium channels open, allowing Na⁺ to flow in, depolarizing the neuron. It’s an all-or-nothing event where only frequency changes, not amplitude.
What is depolarization?
Depolarization is the process of Na⁺ ions entering the neuron, making the interior less negative and triggering an action potential.
What is the refractory period?
The refractory period (~1 ms) occurs when sodium channels close and inactivate after firing, limiting firing rate to around 500–800 impulses per second.
