The left digit effect in a complex judgment task: Evaluating hypothetical college applicants

Abstract

A left digit effect has been broadly observed across judgment and decision‐making contexts ranging from product evaluation to medical treatment decisions to number line estimation. For example, $3.00 is judged to be a much greater cost than $2.99, and “801” is estimated strikingly too far to the right of “798” on a number line. Although the consequences of the effects for judgment and decision behavior have been documented, the sources of the effects are not well established. The goal of the current work is to extend investigations of the left digit effect to a new complex judgment activity and to assess whether the magnitude of the effect at the individual level can be predicted from performance on a simpler number skills task on which the left digit effect has also recently been observed. In three experiments (N = 434), adults completed a judgment task in which they rated the strength of hypothetical applicants for college admission and a self‐paced number line estimation task. In all experiments, a small or medium left digit effect was found in the college admissions task, and a large effect was found in number line estimation. Individual‐level variation was observed, but there was no relationship between the magnitudes of the effects in the two tasks. These findings provide evidence of a left digit effect in a novel multiattribute judgment task but offer no evidence that such performance can be predicted from a simple number skills task such as number line estimation.

Potential moderators of the left digit effect in numerical estimation

“…The effect is widely demonstrated in consumer price judgments (Beracha & Seiler, 2015;Lin & Wang, 2017;MacKillop et al, 2014;Manning & Sprott, 2009;Thomas & Morwitz, 2005 and has been observed in other judgment contexts where numerical information must be evaluated, such as those involving nutritional labels (Choi et al, 2019), car odometer readings (Lacetera et al, 2012), consumer product reviews (Thomas & Morwitz, 2005), and medical records (Olenski et al, 2020). With ongoing efforts to link the left digit effect in number line estimation to other domains (Patalano et al, 2022), we hope that the number line estimation task will have valuable application for assessing, understanding, and ultimately reducing the left digit effect in everyday reasoning contexts.…”

Leading digit bias in hemoglobin thresholds for red cell transfusion

“…12 Leading digit effects are employed in psychological pricing, sway college admissions, and affect stock markets. [13][14][15] Leading digit bias influences clinical judgment in diverse healthcare contexts, including organ transplantation, cardiovascular surgery, oncologic care, and cigarette consumption. [16][17][18][19] We hypothesized that leading digit bias may affect the evaluation of pre-transfusion hemoglobin levels and trigger increased transfusions at clinically relevant leading digit thresholds.…”

“…The bias develops early in life, is relevant for multi‐digit numbers, and is resistant to retraining 12 . Leading digit effects are employed in psychological pricing, sway college admissions, and affect stock markets 13–15 . Leading digit bias influences clinical judgment in diverse healthcare contexts, including organ transplantation, cardiovascular surgery, oncologic care, and cigarette consumption 16–19 …”