Sensation and Perception: Foundations, Cortical Representations, and Psychophysics

Vocabulary flashcards covering core concepts, historical perspectives, psychophysical laws, signal detection theory, and cortical representation studies from Psych 313 lecture notes.

Sensations

The immediate neuronal activity that occurs in receptors when they detect physical energy.

Transduction

The conversion of physical energy from the outside world into neuronal impulses.

Perception

The conscious interpretation of the physical world via our sensations, memory, and previous experience.

Retinal Data Processing Rate

With approximately $1\text{ million}$ ganglion cells per retina ($2\text{ million}$ total), distinction of $\text{roughly } 1\text{ million}$ colors, and neurons firing once every $2\text{ ms}$, the visual system collects $1,000,000,000,000,000$ bits of data every second.

Blindsight

A phenomenon in which patients who believe they are $100\%$ blind perform better than chance on visual tasks due to an intact subcortical pathway that processes stimuli without conscious awareness.

Perceptual Process Cycle

A continuous multi-stage loop involving Stimulus (environmental, attended, and on receptors), Electricity (transduction, transmission, and processing), and Experience and Action (perception, recognition, and action, modified by knowledge).

Plato (~400 B.C.)

Ancient Greek philosopher who provided the first written acknowledgement that human perceptions may not agree with reality, famously illustrated by the Allegory of the Cave.

Aristotle (~350 B.C.)

Ancient Greek philosopher who was the first to recognize the brain as the center of intelligence, though he could not conduct experiments because vivisection was forbidden in Ancient Greece.

Mind-Body Problem

The philosophical debate regarding whether the mind and physical body are separate entities, famously championed by René Descartes.

Gustav Fechner

A physicist who proposed that the mind must be measured scientifically, laying the groundwork for experimental psychophysics.

Ernst Weber

A researcher who observed that human sensitivity to stimulus changes is relative, showing that people are better at detecting differences when background stimulation is low.

Weber-Fechner Law

The mathematical principle $S = k \log(R)$, stating that the subjective perception of a stimulus is logarithmically related to its physical intensity.

Psychophysical Threshold

The stimulus intensity level at which an observer can detect the stimulus $50\%$ of the time; it is mathematically the inverse of sensitivity.

Signal Detection Decision Matrix

A classification system mapping response (yes or no) against signal presence (present or absent), resulting in hits, false alarms, misses, and correct rejections.

Hit (Signal Detection)

A decision outcome in Signal Detection Theory where the signal is present and the observer responds 'yes'.

False Alarm (Signal Detection)

A decision outcome in Signal Detection Theory where the signal is absent but the observer responds 'yes'.

Miss (Signal Detection)

A decision outcome in Signal Detection Theory where the signal is present but the observer responds 'no'.

Correct Rejection (Signal Detection)

A decision outcome in Signal Detection Theory where the signal is absent and the observer responds 'no'.

Criterion (Signal Detection)

The internal threshold or decision boundary chosen by an observer, which determines the ratio of hits to false alarms.

d' (d-prime)

A metric in Signal Detection Theory representing the mathematical distance between the noise distribution and the signal-plus-noise distribution.

Receiver Operating Characteristic (ROC) Curves

Graphical plots in Signal Detection Theory that evaluate observer performance by comparing sensitivity against selectivity.

Sensitivity (Signal Detection)

In Signal Detection Theory, the proportion calculated as $\text{Sensitivity} = \frac{\text{hits}}{\text{false alarms}}$.

Selectivity (Signal Detection)

In Signal Detection Theory, the proportion calculated as $\text{Selectivity} = \frac{\text{correct rejections}}{\text{misses}}$.

Duncan and Boynton (2007) Study

Research demonstrating that behavioral tactile acuity in individual digits directly correlates with the scale of cortical representation in Area 1 of the somatosensory cortex.