RT Journal Article
T1 Improving the estimation of psychometric functions in 2AFC discrimination tasks.
A1 García Pérez, Miguel Ángel
A1 Alcalá Quintana, Rocío
AB Ulrich and Vorberg (2009) presented a method that fits distinct functions for each order of presentation of standard and test stimuli in a two-alternative forced-choice (2AFC) discrimination task, which removes the contaminating influence of order effects from estimates of the difference limen. The two functions are fitted simultaneously under the constraint that their average evaluates to 0.5 when test and standard have the same magnitude, which was regarded as a general property of 2AFC tasks. This constraint implies that physical identity produces indistinguishability, which is valid when test and standard are identical except for magnitude along the dimension of comparison. However, indistinguishability does not occur at physical identity when test and standard differ on dimensions other than that along which they are compared (e.g., vertical and horizontal lines of the same length are not perceived to have the same length). In these cases, the method of Ulrich and Vorberg cannot be used. We propose a generalization of their method for use in such cases and illustrate it with data from a 2AFC experiment involving length discrimination of horizontal and vertical lines. The resultant data could be fitted with our generalization but not with the method of Ulrich and Vorberg. Further extensions of this method are discussed.
SN 1664-1078
YR 2011
FD 2011-05-11
LK https://hdl.handle.net/20.500.14352/44903
UL https://hdl.handle.net/20.500.14352/44903
LA eng
NO Ministerio de Ciencia e Innovación (MICINN)
DS Docta Complutense
RD 5 abr 2025