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Psychometric functions for detection and discrimination with and without flankers
Miguel A García-Pérez1, Rocío Alcalá-Quintana, Russell L Woods
1Departamento de Metodología, Facultad de Psicología, Universidad Complutense, Campus de Somosaguas, 28223, Madrid, Spain. miguel@psi.ucm.es
Flanking stimuli broaden psychometric functions and lower detection thresholds. However, these effects diminish at higher contrast levels, particularly for discrimination tasks.
Area of Science:
- Visual perception
- Psychophysics
Background:
- Flanking stimuli are known to influence visual detection and discrimination.
- Previous research indicates effects on psychometric function broadening and threshold lowering.
Purpose of the Study:
- To investigate the impact of flanking stimuli across the entire contrast continuum.
- To determine if effects on psychometric functions persist at higher contrast levels.
Main Methods:
- Measurement of psychometric functions for detection and discrimination.
- Comparison of functions with and without flanking stimuli.
- Analysis of threshold-versus-contrast (TvC) curves.
Main Results:
- Lowered detection thresholds and broader psychometric functions were confirmed with flankers.
- Discrimination thresholds remained similar with or without flankers.
- Broadening effects disappeared at high standard contrast levels, with functions becoming nearly identical.
Conclusions:
- Flanker effects on psychometric functions are contrast-dependent.
- Differences in literature may stem from psychophysical procedure variations.
- Model fitting success does not inherently validate the model itself.
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