Ehrenstein and Ehrenstein (1999)

Origin of Psychophysics: Introduced by Fechner in 1860 as a method to study the relationship between body (physical processes) and mind (phenomenal experiences).
Key Concept: Body and mind are different reflections of the same reality, with brain processes reflecting in mental experiences. Fechner’s work is an early precursor to modern neuroscience.
Goals of the Chapter: To present Fechner’s psychophysical techniques and modern extensions helpful to neuroscientists studying mind-brain relationships.

Inner Psychophysics: Relation of sensations to the underlying neural processes. Fechner’s theory was theoretical due to lack of physiological recording methods.
Outer Psychophysics: Studies the relationship between sensations and physical properties of stimuli.
Historical Influence: Psychophysical methods influenced the development of experimental psychology and sensory physiology, credited to pioneers like Aubert, Helmholtz, and Weber.

Advancements: New objective methods (e.g., EEG, MEG, PET, fMRI) allow direct study of sensory and brain processes, leading to a synthesis of classic psychophysics with modern neuroscience.
Correlational Research: Combines subjective and objective measures of sensory events, confirming and complementing findings in neurophysiology.
Development of Methods: Psychophysical methods are being established as critical tools in neuroscience research, especially correlating perception with neural activity.

Objective of Psychophysics: Objectification of subjective experiences linked to physical stimuli, through systematic manipulation of stimulus characteristics.
Types of Tasks: Tasks may involve detection, identification, discrimination, and scaling of sensory stimuli, revealing how perceptual judgments are made under different stimuli conditions.

Threshold Measurements: Basic function of sensory systems, requiring energy detection and determining absolute and difference thresholds.
Method of Adjustment: Subjects adjust stimulus intensity to detect thresholds.
Method of Limits: Gradually changing stimulus intensity while recording observer responses to define thresholds.
Method of Constant Stimuli: Presenting fixed stimulus values multiple times to derive psychometric functions reflecting detection probabilities.
Adaptive Testing: Adjusts stimulus levels based on past responses (e.g., staircase method, Best PEST).
Forced-Choice Methods: Observer must respond for every trial, minimizing subjectivity and allowing measures of bias and sensitivity.
Signal Detection Theory (SDT): Measures sensitivity and bias by analyzing hit and false alarm rates to quantify decision-making in perceptual tasks.

Chronometric Methods: Measurement of reaction times (RT) to assess perceptual differences and processing ease.
Scaling Methods: Assigning numbers to perceptual experiences; techniques include category scaling and magnitude estimation.
Cross-Modality Matching: Adjusting stimulus intensity across modalities to equate perceived intensities without numerical assignment.

Animal Studies: Adapted psychophysical methods to study sensory systems in non-human species, allowing interspecies comparisons and insights into sensory mechanisms.
Behavioral Conditioning Methods: Utilizing reflexive and operant conditioning to establish thresholds and performance metrics in animals during sensory tasks.

Auditory Motion Aftereffect: Investigating motion aftereffect analogs in auditory perception through psychophysical methods.
Interocular Latency Differences in Neurological Patients: Studying latency differences to assess visual pathway integrity in multiple sclerosis patients, with findings correlating with VEP.
Perceptive Fields in Monkey and Man: Measuring perceptive fields using the Westheimer paradigm, revealing similarities and differences in perceptual processing between species.

Emerging Discipline: The synthesis of psychophysical methods with neuroscience sheds light on sensory and perceptual processes.
Methodological Flexibility: There is no one-size-fits-all methodology; choosing appropriate techniques for specific research questions is crucial.

Fechner, G. T. (1860/1966). Elements of Psychophysics.
Green, D. M., & Swets, J. A. (1966). Signal Detection Theory and Psychophysics.
Ehrenstein, W. H. (1994). Auditory Aftereffects Following Simulated Motion.