DNA Evidence as the Basis for Conviction

The sufficiency of DNA evidence alone, with regard to convicting accused persons, has been interrogated and challenged in criminal cases. The availability of offender databases and the increasing sophistication of crime scene recovery of evidence have resulted in a new type of prosecution in which the State's case focuses on match statistics to explain the significance of a match between the accused's DNA profile and the crime-scene evidence. A number of such cases have raised critical jurisprudential questions about the proper role of probabilistic evidence, and the misapprehension of match statistics by courts. This article, with reference to selected cases from specific jurisdictions, investigates the issue of DNA evidence as the exclusive basis for conviction and important factors such as primary, secondary and tertiary transfer, contamination, cold hits and match probability which can influence the reliability of basing a conviction on DNA evidence alone, are discussed.

Is Probabilistic Evidence a Source of Knowledge

We report a series of experiments examining whether people ascribe knowledge for true beliefs based on probabilistic evidence. Participants were less likely to ascribe knowledge for beliefs based on probabilistic evidence than for beliefs based on perceptual evidence or testimony providing causal information. Denial of knowledge for beliefs based on probabilistic evidence did not arise because participants viewed such beliefs as unjustified, nor because such beliefs leave open the possibility of error. These findings rule out traditional philosophical accounts for why probabilistic evidence does not produce knowledge. The experiments instead suggest that people deny knowledge because they distrust drawing conclusions about an individual based on reasoning about the population to which it belongs, a tendency previously identified by “judgment and decision making” researchers. Consistent with this, participants were more willing to ascribe knowledge for beliefs based on probabilistic evidence that is specific to a particular case. 2016 APA, all rights reserved)

It’s all relative: Explanationism and probabilistic evidence theory

I provide a brief comment on Allen & Pardo’s “Relative plausibility and its critics”. I agree that their relative plausibility explanationism (RPE) provides an attractive positive description of fact finding in litigation. But unlike Allen & pardo, I see RPE as methodologically consistent with the leading conceptions of evidentiary probabilism, Bayesianism and likelihoodism. Thus, I argue, the best view of the relationship between the approaches is that RPE is a friendly amendment to–because it provides a positive foundation for–probabilism.

Continuous track paths reveal additive evidence integration in multistep decision making

Multistep decision making pervades daily life, but its underlying mechanisms remain obscure. We distinguish four prominent models of multistep decision making, namely serial stage, hierarchical evidence integration, hierarchical leaky competing accumulation (HLCA), and probabilistic evidence integration (PEI). To empirically disentangle these models, we design a two-step reward-based decision paradigm and implement it in a reaching task experiment. In a first step, participants choose between two potential upcoming choices, each associated with two rewards. In a second step, participants choose between the two rewards selected in the first step. Strikingly, as predicted by the HLCA and PEI models, the first-step decision dynamics were initially biased toward the choice representing the highest sum/mean before being redirected toward the choice representing the maximal reward (i.e., initial dip). Only HLCA and PEI predicted this initial dip, suggesting that first-step decision dynamics depend on additive integration of competing second-step choices. Our data suggest that potential future outcomes are progressively unraveled during multistep decision making.