Psychophysics and Sensation

A set of vocabulary flashcards covering key concepts related to psychophysics, sensation, and perception.

Sensation

The detection of physical energy by sensory organs such as the eyes, ears, skin, and tongue.

Perception

The process of interpreting sensory information to derive meaning or conclusions about the environment.

Sensory Organs

Biological systems specialized to detect environmental stimuli (e.g., eyes for light, skin for touch).

Psychophysics

The scientific study of the relationship between physical stimuli and the sensations and perceptions they produce.

Absolute Threshold

The minimum intensity of a stimulus that can be reliably detected.

Difference Threshold

The smallest difference between two stimuli that can be reliably detected.

Sensory Threshold

A general term referring to the minimum stimulus intensity required to produce a sensation.

Loudness

The perceived magnitude of sound intensity, a psychological response to physical decibels.

Pitch

The perceived frequency of a sound wave, distinguishing high from low tones.

Psychophysical Methods

Experimental techniques used to determine sensory thresholds.

Method of Constant Stimuli

A psychophysical method where stimuli of different intensities are presented in random order and detection rates are recorded.

Threshold (50%)

In the method of constant stimuli, the stimulus intensity at which a participant detects the stimulus 50% of the time.

Method of Limits

A psychophysical method where stimulus intensity is gradually increased or decreased to determine detection point.

Crossover Point

The intensity value at which a participant’s response changes from detection to non-detection or vice versa.

Just Noticeable Difference (JND)

The smallest detectable difference in stimulus intensity that a person can reliably perceive.

Weber’s Law

The principle stating that the JND is a constant proportion of the original stimulus intensity.

Weber Fraction

The constant ratio representing the proportion of change needed to detect a difference in stimulus intensity.

Modified Weber’s Law

An extension of Weber’s law that accounts for low-intensity stimulus detection.

Sensory Noise

Background neural activity that influences perception, especially near threshold levels.

Neural Discrimination

The brain's ability to distinguish between different levels of stimulation based on changes in neural activity.

Constant a (in Weber’s Law)

A small value added in the modified version of Weber’s Law to reflect sensory noise effects.

Fechner’s Law

A psychophysical rule stating that the perceived intensity of a stimulus increases logarithmically with its physical intensity.

Unit of the Mind (Fechner)

The smallest perceptual increment, equated to a single Just Noticeable Difference (JND).

Psychological Scaling

The process of assigning numerical values to perceived sensory magnitudes based on physical stimuli.

Logarithmic Sensation Function

A function where equal steps in perception correspond to multiplicative increases in physical stimulus.

Diminishing Sensitivity

The concept that as physical intensity increases, it produces smaller increases in perceived intensity.

Magnitude Estimation

A psychophysical method where participants assign numbers to stimuli reflecting the perceived strength of sensation.

Stevens’ Law

A power law stating that perceived sensation is a power function of stimulus intensity.

Exponent b (in Stevens’ Law)

A value determining the rate at which sensation grows relative to stimulus intensity.

Power Function of Sensation

A function where changes in perceived magnitude follow a nonlinear relationship to stimulus strength.

Psychophysical Scaling

The process of quantifying how much sensation increases as stimulus intensity increases.

Objective Measurement

A method where outcomes are directly observable and verifiable.

Subjective Rating Data

Information gathered by asking participants to assign numerical values to their perceptual experiences.

Psychophysical Law Violation

A scenario where a theoretical law like Fechner’s fails to align with real perceptual responses.

Equally Perceived JNDs (Assumption)

The assumption in Fechner’s law that each just noticeable difference corresponds to an equal increase in perceptual magnitude.