Limits...
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.


Related in: MedlinePlus

Variable difficulty (η = 0.1) in the free response paradigm. Minimum MRT is achieved when all bias is accounted for by a shift in starting point z. Bias β = 0.8, boundary separation a = 0.12. Top panel: Parameter combinations of starting point as a ratio of boundary separation z/a and shift in drift rate criterion vc that lead to the same fixed level of accuracy (90% for v = 0.2, 95% for v = 0.3). Bottom panel: Mean RT that corresponds to the parameter combinations of the top panel.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3351677&req=5

Figure 7: Variable difficulty (η = 0.1) in the free response paradigm. Minimum MRT is achieved when all bias is accounted for by a shift in starting point z. Bias β = 0.8, boundary separation a = 0.12. Top panel: Parameter combinations of starting point as a ratio of boundary separation z/a and shift in drift rate criterion vc that lead to the same fixed level of accuracy (90% for v = 0.2, 95% for v = 0.3). Bottom panel: Mean RT that corresponds to the parameter combinations of the top panel.

Mentions: The top-left panel of Figure 7 shows the set of parameter values of starting point z and drift rate shift vc that lead to a percentage correct of 90% with a mean drift rate v = 0.2. The top-right panel shows the set of parameter values of starting point z and drift rate shift vc that lead to a percentage correct of 95% with a mean drift rate v = 0.3. For both panels, boundary separation a = 0.12, bias β = 0.8, and standard deviation of drift rate η = 0.1. The bottom panels of Figure 7 show corresponding values of MRT. The MRT results show that as for fixed difficulty, the lowest value for MRT is reached when all bias is accounted for by a shift in starting point z.


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)

Variable difficulty (η = 0.1) in the free response paradigm. Minimum MRT is achieved when all bias is accounted for by a shift in starting point z. Bias β = 0.8, boundary separation a = 0.12. Top panel: Parameter combinations of starting point as a ratio of boundary separation z/a and shift in drift rate criterion vc that lead to the same fixed level of accuracy (90% for v = 0.2, 95% for v = 0.3). Bottom panel: Mean RT that corresponds to the parameter combinations of the top panel.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: Variable difficulty (η = 0.1) in the free response paradigm. Minimum MRT is achieved when all bias is accounted for by a shift in starting point z. Bias β = 0.8, boundary separation a = 0.12. Top panel: Parameter combinations of starting point as a ratio of boundary separation z/a and shift in drift rate criterion vc that lead to the same fixed level of accuracy (90% for v = 0.2, 95% for v = 0.3). Bottom panel: Mean RT that corresponds to the parameter combinations of the top panel.
Mentions: The top-left panel of Figure 7 shows the set of parameter values of starting point z and drift rate shift vc that lead to a percentage correct of 90% with a mean drift rate v = 0.2. The top-right panel shows the set of parameter values of starting point z and drift rate shift vc that lead to a percentage correct of 95% with a mean drift rate v = 0.3. For both panels, boundary separation a = 0.12, bias β = 0.8, and standard deviation of drift rate η = 0.1. The bottom panels of Figure 7 show corresponding values of MRT. The MRT results show that as for fixed difficulty, the lowest value for MRT is reached when all bias is accounted for by a shift in starting point z.

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.


Related in: MedlinePlus