Abstract
Park and Brannon (2013, https://doi.org/10.1177/0956797613482944) found that practicing non-symbolic approximate arithmetic increased performance on an objective numeracy task, specifically symbolic arithmetic. Manipulating objective numeracy would be useful for many researchers, particularly those who wish to investigate causal effects of objective numeracy on performance. Objective numeracy has been linked to performance in multiple areas, such as judgment-and-decision-making (JDM) competence, but most existing studies are correlational. Here, we expanded upon Park and Brannon’s method to experimentally manipulate objective numeracy and we investigated whether numeracy’s link with JDM performance was causal. Experimental participants drawn from a diverse internet sample trained on approximate-arithmetic tasks whereas active control participants trained on a spatial working-memory task. Numeracy training followed a 2 × 2 design: Experimental participants quickly estimated the sum of OR difference between presented numeric stimuli, using symbolic numbers (i.e., Arabic numbers) OR non-symbolic numeric stimuli (i.e., dot arrays). We partially replicated Park and Brannon’s findings: The numeracy training improved objective-numeracy performance more than control training, but this improvement was evidenced by performance on the Objective Numeracy Scale, not the symbolic arithmetic task. Subsequently, we found that experimental participants also perceived risks more consistently than active control participants, and this risk-consistency benefit was mediated by objective numeracy. These results provide the first known experimental evidence of a causal link between objective numeracy and the consistency of risk judgments.
Highlights
The Causal Impact of Objective Numeracy on Judgments: Improving Numeracy via Symbolic and Non-Symbolic Approximate Arithmetic Training Yields More Consistent Risk Judgments
It may be that more objectively numerate individuals: 1) habitually make more numeric comparisons and transformations (Peters et al, 2006; Peters, Fennema, et al, 2019); 2) engage spontaneously in greater deliberation about numeric information (Ghazal, Cokely, & Garcia-Retamero, 2014; Obrecht & Chesney, 2016; Peters et al, 2006); 3) have a more accurate understanding of numeric magnitudes that they use to value numeric information in decisions (Peters, Slovic, Västfjäll, & Mertz, 2008; Schley & Peters, 2014); and/or 4) have adequate efficacy with numbers, enabling them to make consistent judgments based on numeric information (Peters & Bjälkebring, 2015; Rolison et al, 2016). We note these explanations are not mutually exclusive. The latter two mechanisms, are less likely in the present case given that we found no significant effects of numeracy versus memory training on symbolic number mapping or subjective numeracy
Our effects were smaller than those found by Park and Brannon (2013, 2014) and the specific effects found were different, we confirmed that practice with approximate arithmetic yielded benefits to objective numeracy
Summary
Participants in this study were recruited online via Amazon Mechanical Turk (MTurk) over a 2-week period, in small cohorts of no more than 50 individuals. We initially recruited 935 individuals via MTurk who began the pretest. We excluded 66 participants who responded from outside of the United States, and an additional 18 who did not identify as native English speakers, leaving an initial sample n of 851. Participants were paid $2.00 to complete the pretest, $3.00 to complete the posttest, and $3.00 for each training session in which they participated (up to 6 possible), for a maximum total possible reimbursement of $23.00 in the training conditions and $5.00 in the non-intervention control condition. Participants were paid promptly, typically within 24 hours of each session, to encourage retention
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