Psychophysics and Sensory Thresholds: Perception and Mathematical Models

Subconscious decision-making

The process our brains engage in regarding what to sense and how to interpret sensory input.

Bayesian probability

An approach to inference that interprets incoming information based on what is possible and likely based on pre-existing knowledge.

Information theory

A branch of mathematics that explores how we learn things about the world based on the improbability of events.

Thresholds

Finding the limits of what can be perceived.

Suprathreshold scaling

Relating the intensity of perception relative to the physical magnitude of the stimulus.

Discrimination

Evaluating which stimuli we can distinguish apart and which ones seem the same.

Functionalism

The idea that any systems that make the same responses to all possible stimuli are effectively identical, regardless of their form.

Turing test

A test to see if a computer and a person can be distinguished from each other.

Chinese Room argument

An argument by Searle that distinguishes between semantic knowledge and syntactic knowledge.

Psychophysics

The science of defining relationships between physical and psychological (subjective) events.

Just noticeable difference (JND)

The smallest detectable difference between two stimuli or the minimum change in a stimulus that can be correctly judged from a reference stimulus.

Weber's Law

The size of the JND for a stimulus is a constant proportion of the size of the stimulus.

Weber's Law equation

ds = k (dI/I), where ds is the change in sensation, dI is the change in stimulus intensity, and k is a constant.

Supra threshold scaling

The method of measuring how strong a stimulus seems, which is a private experience.

Fechner's Law

S = k ln(I), which states that perceived intensity increases as a logarithmic function of physical stimulus.

Magnitude estimation

A psychophysical method where participants assign values according to the perceived magnitudes of stimuli.

Cross-modality matching

A technique where participants match the intensity of a sensation in one modality with that in another modality.

Stevens' Law

A principle describing the relationship between stimulus magnitude and resulting sensation magnitude, where sensation is proportional to stimulus magnitude raised to an exponent.

Absolute threshold

The minimum amount of stimulation necessary to detect a stimulus 50% of the time.

Recognition threshold

The minimum amount of stimulation necessary for a person to identify a stimulus correctly 50% of the time.

Method of constant stimuli

A psychophysical method where many stimuli are presented one at a time, ranging from rarely to almost always perceivable.

Methods of limits

A psychophysical method where the magnitude of a single stimulus or the difference between two stimuli is varied.

Method of adjustment

A psychophysical method where the participant controls the stimulus intensity directly to reach a barely detectable level.