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Daniel Shepherd - One of the best experts on this subject based on the ideXlab platform.
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The single interval adjustment matrix (SIAM) yes–no task: an empirical assessment using auditory and gustatory stimuli
Attention perception & psychophysics, 2011Co-Authors: Daniel Shepherd, Michael J. Hautus, Miriam A. Stocks, Siew Young QuekAbstract:The SIAM yes–no task is an efficient bias-free adaptive procedure for estimating absolute thresholds, though it arguably requires further evaluation prior to its adoption into mainstream psychological research. We report two experiments undertaken in the auditory and gustatory modalities designed to assess the accuracy and efficiency of the SIAM method. In the first experiment, estimates of absolute thresholds for 1000-Hz tones obtained using a Two-Alternative Forced Choice adaptive procedure were compared to those obtained using both the SIAM yes–no task and a modification of the SIAM task incorporating the method of free response, the SIAM-rapid. In Experiment 2, we compared absolute thresholds for sucrose in solution obtained with either a Two-Alternative Forced Choice adaptive procedure or the SIAM yes–no task. Both experiments demonstrated the efficiency and validity of the SIAM approach, with SIAM thresholds proving to be equivalent to those obtained in the Two-Alternative Forced Choice tasks and to those reported in the literature.
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Decision strategies for the Two-Alternative Forced Choice reminder paradigm.
Attention perception & psychophysics, 2010Co-Authors: Michael J. Hautus, Daniel Shepherd, Mei PengAbstract:The decision strategy adopted by an observer in a psychophysical procedure may be established by comparing estimates of sensitivity obtained by using detection-theoretic models based on each of the available decision strategies. Estimates of sensitivity obtained from 10 observers on auditory-level discrimination tasks using the yes/no, Two-Alternative Forced Choice (2AFC), and 2AFC with reminder (2AFCR; sometimes called duo–trio) procedures were compared in order to determine the decision strategy used by the judges in the 2AFCR procedure. 2AFCR permits at least three decision strategies: differencing, likelihood ratio, and comparison of distances. The latter strategy has frequently been assumed in the analysis of duo–trio data in the sensory evaluation literature. The present study demonstrates that the comparison-of-distances strategy was not used by 9 of the 10 observers in this auditory experiment. The nature of the instructions given to the observers had no measurable impact on the decision strategy that they adopted.
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THE EFFECT OF A REMINDER STIMULUS ON THE DECISION STRATEGY ADOPTED IN THE Two-Alternative Forced-Choice PROCEDURE
2009Co-Authors: Michael J. Hautus, Daniel Shepherd, Mei PengAbstract:The decision strategy adopted by an observer in a psychophysical task may be established bycomparing estimates of sensitivity obtained by using detection-theoretic models that assumethe various available decision strategies. The performance of ten observers on an auditorylevel discrimination task using the yes-no, two alternative Forced Choice (2AFC), and 2AFCwith reminder (2AFCR; sometimes called duo-trio) procedures was compared to determinethe decision strategy used in the 2AFCR procedure. This procedure permits at least threedecision strategies: differencing, likelihood ratio, and comparison of distances. The latterstrategy has been frequently assumed in the analysis of duo-trio data in the sensoryevaluation literature. The current study demonstrates that the comparison of distancesstrategy was not used by nine of the ten observers.
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sucrose detection and the stability of the 2 afc procedure in the presence of a confounding variable
Journal of Sensory Studies, 2008Co-Authors: Daniel Shepherd, Siew Young Quek, Sreeni PathiranaAbstract:This study attempted to measure absolute thresholds for sucrose in aqueous solution for 51 experienced judges. Two experiments utilizing the Two-Alternative Forced-Choice (2-AFC) procedure generated 6-point psychometric functions plotting percentage correct as a function of sucrose concentration. In both experiments, the judges were divided into two groups and tested in either purpose-built sensory booths or on open tables situated in a laboratory. In the first experiment, the influence of a confounding variable was apparent, with nonmonotonic psychometric functions being obtained. In experiment II, the confounding variable was eliminated, permitting the estimation of absolute thresholds. In both experiments, there was no main effect of gender or session, though there was an effect of testing locality (P < 0.05). Data are reported to emphasize the importance of controlling extraneous variables and to demonstrate the robustness of the 2-AFC procedure. PRACTICAL APPLICATIONS This research contributes to an otherwise impoverished database on the detection of sucrose in a solution. The uses of the research include estimates of sucrose detection thresholds for comparative purposes; confirmation of the stability of the Two-Alternative Forced-Choice procedure; the utility of using formal testing areas as opposed to ad hoc testing stations; and the dangers of utilizing substandard experimental equipment while conducting research of this nature.
Rocío Alcalá-quintana - One of the best experts on this subject based on the ideXlab platform.
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Order effects in Two-Alternative Forced-Choice tasks invalidate adaptive threshold estimates
Behavior Research Methods, 2020Co-Authors: Miguel A. García-pérez, Rocío Alcalá-quintanaAbstract:Adaptive psychophysical methods are widely used for the quick estimation of percentage points (thresholds) on psychometric functions for Two-Alternative Forced-Choice (2AFC) tasks. The use of adaptive methods is supported by numerous simulation studies documenting their performance, which have shown that thresholds can be reasonably estimated with them when their founding assumptions hold. One of these assumptions is that the psychometric function is invariant, but empirical evidence is mounting that human performance in 2AFC tasks needs to be described by two different psychometric functions, one that holds when the test stimulus is presented first in the 2AFC trial and a different one that holds when the test is presented second. The same holds when presentations are instead simultaneous at two spatial locations rather than sequential. We re-evaluated the performance of adaptive methods in the presence of these order effects via simulation studies and an empirical study with human observers. The simulation study showed that thresholds are severely overestimated by adaptive methods in these conditions, and the empirical study corroborated these findings. These results question the validity of threshold estimates obtained with adaptive methods that incorrectly assume the psychometric function to be invariant with presentation order. Alternative ways in which thresholds can be accurately estimated in the presence of order effects are discussed.
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Testing equivalence with repeated measures: tests of the difference model of Two-Alternative Forced-Choice performance
The Spanish journal of psychology, 2011Co-Authors: Miguel A. García-pérez, Rocío Alcalá-quintanaAbstract:Solving theoretical or empirical issues sometimes involves establishing the equality of two variables with repeated measures. This defies the logic of null hypothesis significance testing, which aims at assessing evidence against the null hypothesis of equality, not for it. In some contexts, equivalence is assessed through regression analysis by testing for zero intercept and unit slope (or simply for unit slope in case that regression is Forced through the origin). This paper shows that this approach renders highly inflated Type I error rates under the most common sampling models implied in studies of equivalence. We propose an alternative approach based on omnibus tests of equality of means and variances and in subject-by-subject analyses (where applicable), and we show that these tests have adequate Type I error rates and power. The approach is illustrated with a re-analysis of published data from a signal detection theory experiment with which several hypotheses of equivalence had been tested using only regression analysis. Some further errors and inadequacies of the original analyses are described, and further scrutiny of the data contradict the conclusions raised through inadequate application of regression analyses.
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THE DIFFERENCE MODEL WITH GUESSING EXPLAINS INTERVAL BIAS IN TWO‐ALTERNATIVE Forced‐Choice DETECTION PROCEDURES
Journal of Sensory Studies, 2010Co-Authors: Miguel A. García-pérez, Rocío Alcalá-quintanaAbstract:ABSTRACT The standard difference model of Two-Alternative Forced-Choice (2AFC) tasks implies that performance should be the same when the target is presented in the first or the second interval. Empirical data often show “interval bias” in that percentage correct differs significantly when the signal is presented in the first or the second interval. We present an extension of the standard difference model that accounts for interval bias by incorporating an indifference zone around the null value of the decision variable. Analytical predictions are derived which reveal how interval bias may occur when data generated by the guessing model are analyzed as prescribed by the standard difference model. Parameter estimation methods and goodness-of-fit testing approaches for the guessing model are also developed and presented. A simulation study is included whose results show that the parameters of the guessing model can be estimated accurately. Finally, the guessing model is tested empirically in a 2AFC detection procedure in which guesses were explicitly recorded. The results support the guessing model and indicate that interval bias is not observed when guesses are separated out. PRACTICAL APPLICATIONS This research provides practicing sensory scientists with an alternative approach to obtaining unbiased sensitivity measures from Two-Alternative Forced-Choice detection or discrimination tasks in which a “no-preference” response has been allowed and “placebo” trials are included (i.e., trials in which both stimuli are identical). Experiments designed in this way imply what can naturally be referred to as a Two-Alternative non-Forced-Choice task. Analysis of the resultant data under the difference model with guessing allows obtaining an unbiased measure of sensitivity as well as an estimate of the size of the indifference zone, whether in detection or in discrimination tasks. In the latter, this indifference zone explains why a non-negligible percentage of preference responses are given in “placebo” trials during paired discrimination tests and, through the guessing model, it also accounts for a non-negligible number of nonidentical calls to actually identical stimuli in same–different tests.
Jonathan D Cohen - One of the best experts on this subject based on the ideXlab platform.
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Optimality and Some of Its Discontents: Successes and Shortcomings of Existing Models for Binary Decisions
Topics in cognitive science, 2014Co-Authors: Philip Holmes, Jonathan D CohenAbstract:We review how leaky competing accumulators (LCAs) can be used to model decision making in Two-Alternative, Forced-Choice tasks, and we show how they reduce to drift diffusion (DD) processes in special cases. As continuum limits of the sequential probability ratio test, DD processes are optimal in producing decisions of specified accuracy in the shortest possible time. Furthermore, the DD model can be used to derive a speed–accuracy trade-off that optimizes reward rate for a restricted class of two alternative Forced-Choice decision tasks. We review findings that compare human performance with this benchmark, and we reveal both approximations to and deviations from optimality. We then discuss three potential sources of deviations from optimality at the psychological level—avoidance of errors, poor time estimation, and minimization of the cost of control—and review recent theoretical and empirical findings that address these possibilities. We also discuss the role of cognitive control in changing environments and in modulating exploitation and exploration. Finally, we consider physiological factors in which nonlinear dynamics may also contribute to deviations from optimality.
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The physics of optimal decision making: A formal analysis of models of performance in Two-Alternative Forced-Choice tasks
Psychological Review, 2006Co-Authors: Rafal Bogacz, Jeff Moehlis, Philip Holmes, Eric Brown, Jonathan D CohenAbstract:In this article, the authors consider optimal decision making in Two-Alternative Forced-Choice (TAFC) tasks. They begin by analyzing 6 models of TAFC decision making and show that all but one can be reduced to the drift diffusion model, implementing the statistically optimal algorithm (most accurate for a given speed or fastest for a given accuracy). They prove further that there is always an optimal trade-off between speed and accuracy that maximizes various reward functions, including reward rate (percentage of correct responses per unit time), as well as several other objective functions, including ones weighted for accuracy. They use these findings to address empirical data and make novel predictions about performance under optimality.
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Mechanisms underlying dependencies of performance on stimulus history in a Two-Alternative Forced-Choice task
Cognitive Affective & Behavioral Neuroscience, 2002Co-Authors: Raymond Y. Cho, Leigh E. Nystrom, Eric T. Brown, Andrew D. Jones, Todd S. Braver, Philip J. Holmes, Jonathan D CohenAbstract:In Choice reaction time tasks, response times and error rates demonstrate differential dependencies on the identities of up to four stimuli preceding the current one. Although the general profile of reaction times and error rates, when plotted against the stimulus histories, may seem idiosyncratic, we show that it can result from simple underlying mechanisms that take account of the occurrence of stimulus repetitions and alternations. Employing a simple connectionist model of a Two-Alternative ForcedChoice task, we explored various combinations of repetition and alternation detection schemes in an attempt to account for empirical results from the literature and from our own studies. We found that certain combinations of the repetition and the alternation schemes provided good fits to the data, suggesting that simple mechanisms may serve to explain the complicated but highly reproducible higher order dependencies of task performance on stimulus history.
David E Huber - One of the best experts on this subject based on the ideXlab platform.
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Testing Signal-Detection Models of Yes/No and Two-Alternative Forced-Choice Recognition Memory
Journal of Experimental Psychology: General, 2009Co-Authors: Yoonhee Jang, John T. Wixted, David E HuberAbstract:The current study compared 3 models of recognition memory in their ability to generalize across yes/no and 2-alternative Forced-Choice (2AFC) testing. The unequal-variance signal-detection model assumes a continuous memory strength process. The dual-process signal-detection model adds a thresholdlike recollection process to a continuous familiarity process. The mixture signal-detection model assumes a continuous memory strength process, but the old item distribution consists of a mixture of 2 distributions with different means. Prior efforts comparing the ability of the models to characterize data from both test formats did not consider the role of parameter reliability, which can be critical when comparing models that differ in flexibility. Parametric bootstrap simulations revealed that parameter regressions based on separate fits of each test type only served to identify the least flexible model. However, simultaneous fits of receiver-operating characteristic data from both test types with goodness-of-fit adjusted with Akaike's information criterion (AIC) successfully recovered the true model that generated the data. With AIC and simultaneous fits to real data, the unequal-variance signal-detection model was found to provide the best account across yes/no and 2AFC testing.
Shuji Mori - One of the best experts on this subject based on the ideXlab platform.
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Spatial-frequency uncertainty and cuing effects on psychometric functions for contrast detection.
Psychonomic bulletin & review, 2002Co-Authors: Yoshio Ohtani, Shuji MoriAbstract:In the present study, the effects of spatial-frequency uncertainty and cuing on psychometric functions for contrast detection of sinusoidal gratings are examined. For this purpose, psychometric functions were collected from 4 subjects under fixed-frequency, randomized-frequency, and cued-frequency conditions. The experiment was conducted with a temporal Two-Alternative Forced-Choice task, and five spatial frequencies in the range of 0.5 and 8.0 c/deg and seven contrast levels for each frequency were used. The results showed that the psychometric functions for the randomized-frequency condition were shallower than those for the fixed-frequency condition, supporting the single-band model for the uncertainty effects (Hubner, 1993a, 1993b). For the cued-frequency condition, the slopes of the functions were not clearly different from those for the randomized condition. These results clearly differ from those of Hubner (1996b), which showed, in the spatial Two-Alternative Forced-Choice task, steeper psychometric functions for the randomized-frequency condition than those for the fixed- and cued-frequency conditions, supporting the multiple-band model (Hubner, 1993a, 1993b). The difference suggests that the single-band model applies to the uncertainty effects in the temporal Forced-Choice task, whereas the multiple-band model does so in the spatial Forced-Choice task.
