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Do the dynamics of prior information depend on task context? An analysis of optimal performance and an empirical test.

van Ravenzwaaij D, Mulder MJ, Tuerlinckx F, Wagenmakers EJ - Front Psychol (2012)

Bottom Line: In this model, prior information or advance knowledge about the correct response can manifest itself as a shift in starting point or as a shift in drift rate criterion.These two mechanisms lead to qualitatively different choice behavior.Firstly, we demonstrate that optimal behavior for biased decision problems is prescribed by a shift in starting point, irrespective of variability in stimulus difficulty.

View Article: PubMed Central - PubMed

Affiliation: Psychological Methods, University of Amsterdam Amsterdam, Netherlands.

ABSTRACT
In speeded two-choice tasks, optimal performance is prescribed by the drift diffusion model. In this model, prior information or advance knowledge about the correct response can manifest itself as a shift in starting point or as a shift in drift rate criterion. These two mechanisms lead to qualitatively different choice behavior. Analyses of optimal performance (i.e., Bogacz et al., 2006; Hanks et al., 2011) have suggested that bias should manifest itself in starting point when difficulty is fixed over trials, whereas bias should (additionally) manifest itself in drift rate criterion when difficulty is variable over trials. In this article, we challenge the claim that a shift in drift criterion is necessary to perform optimally in a biased decision environment with variable stimulus difficulty. This paper consists of two parts. Firstly, we demonstrate that optimal behavior for biased decision problems is prescribed by a shift in starting point, irrespective of variability in stimulus difficulty. Secondly, we present empirical data which show that decision makers do not adopt different strategies when dealing with bias in conditions of fixed or variable across-trial stimulus difficulty. We also perform a test of specific influence for drift rate variability.

No MeSH data available.


Left panel: starting point bias and drift rate criterion bias. Right four panels: MRT (top) and proportion correct (bottom) for fixed (left) and variable (right) difficulty. Dots represent the mean, error bars represent 95% confidence intervals. Con, consistent; Neu, neutral; Inc, inconsistent.
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Figure 8: Left panel: starting point bias and drift rate criterion bias. Right four panels: MRT (top) and proportion correct (bottom) for fixed (left) and variable (right) difficulty. Dots represent the mean, error bars represent 95% confidence intervals. Con, consistent; Neu, neutral; Inc, inconsistent.

Mentions: The left panel of Figure 8 shows both starting point bias and drift rate criterion bias for the fixed difficulty condition and the variable difficulty condition. In the fixed difficulty condition, both the bias in starting point and the bias in drift rate are larger than zero (t(10) = 5.85, p < 0.01, and t(10) = 3.43, p < 0.01, respectively). In the variable difficulty condition, both the bias in starting point and the bias in drift rate also are larger than zero (t(10) = 6.89, p < 0.01, and t(10) = 4.14, p < 0.01, respectively). The right panel of Figure 8 shows MRT and proportion correct for consistent, neutral, and inconsistent stimuli for the fixed and variable difficulty conditions.


Do the dynamics of prior information depend on task context? An analysis of optimal performance and an empirical test.

van Ravenzwaaij D, Mulder MJ, Tuerlinckx F, Wagenmakers EJ - Front Psychol (2012)

Left panel: starting point bias and drift rate criterion bias. Right four panels: MRT (top) and proportion correct (bottom) for fixed (left) and variable (right) difficulty. Dots represent the mean, error bars represent 95% confidence intervals. Con, consistent; Neu, neutral; Inc, inconsistent.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3351677&req=5

Figure 8: Left panel: starting point bias and drift rate criterion bias. Right four panels: MRT (top) and proportion correct (bottom) for fixed (left) and variable (right) difficulty. Dots represent the mean, error bars represent 95% confidence intervals. Con, consistent; Neu, neutral; Inc, inconsistent.
Mentions: The left panel of Figure 8 shows both starting point bias and drift rate criterion bias for the fixed difficulty condition and the variable difficulty condition. In the fixed difficulty condition, both the bias in starting point and the bias in drift rate are larger than zero (t(10) = 5.85, p < 0.01, and t(10) = 3.43, p < 0.01, respectively). In the variable difficulty condition, both the bias in starting point and the bias in drift rate also are larger than zero (t(10) = 6.89, p < 0.01, and t(10) = 4.14, p < 0.01, respectively). The right panel of Figure 8 shows MRT and proportion correct for consistent, neutral, and inconsistent stimuli for the fixed and variable difficulty conditions.

Bottom Line: In this model, prior information or advance knowledge about the correct response can manifest itself as a shift in starting point or as a shift in drift rate criterion.These two mechanisms lead to qualitatively different choice behavior.Firstly, we demonstrate that optimal behavior for biased decision problems is prescribed by a shift in starting point, irrespective of variability in stimulus difficulty.

View Article: PubMed Central - PubMed

Affiliation: Psychological Methods, University of Amsterdam Amsterdam, Netherlands.

ABSTRACT
In speeded two-choice tasks, optimal performance is prescribed by the drift diffusion model. In this model, prior information or advance knowledge about the correct response can manifest itself as a shift in starting point or as a shift in drift rate criterion. These two mechanisms lead to qualitatively different choice behavior. Analyses of optimal performance (i.e., Bogacz et al., 2006; Hanks et al., 2011) have suggested that bias should manifest itself in starting point when difficulty is fixed over trials, whereas bias should (additionally) manifest itself in drift rate criterion when difficulty is variable over trials. In this article, we challenge the claim that a shift in drift criterion is necessary to perform optimally in a biased decision environment with variable stimulus difficulty. This paper consists of two parts. Firstly, we demonstrate that optimal behavior for biased decision problems is prescribed by a shift in starting point, irrespective of variability in stimulus difficulty. Secondly, we present empirical data which show that decision makers do not adopt different strategies when dealing with bias in conditions of fixed or variable across-trial stimulus difficulty. We also perform a test of specific influence for drift rate variability.

No MeSH data available.