Is it a judgment of representativeness? Re-examining the birth sequence problem.

Although all birth orders in the "birth sequence problem" are equiprobable, most participants judge the less representative order as less likely than the more representative order. But this well-known problem confounds representativeness with the direction in which birth orders are compared. We hypothesized and corroborated in three experiments (total N = 1,136) that participants pragmatically infer the birth orders' relative prevalence from the direction of comparison. Experiment 1 found that participants judged the less representative sequence as more common when we reversed the comparison. Experiment 2 reproduced these results despite removing representativeness as a cue. In Experiment 3, participants preferred to place the relatively common sequence as the referent in an inverted "speaker" problem. Our results turn the iconic problem's interpretation on its head: Rather than indicating flawed human cognition, the birth sequence problem illustrates people's ability to adaptively extract subtle linguistic meaning beyond the literal content.

Default sensitivity in attempts at social influence.

While past research has demonstrated the power of defaults to nudge decision makers toward desired outcomes, few studies have examined whether people understand how to strategically set defaults to influence others' choices. A recent paper (Zlatev et al. Proceedings of the National Academy of Sciences, 114, 13643-13648, 2017) found that participants exhibited "default neglect," or the failure to set optimal defaults at better than chance levels. However, we show that this poor performance is specific to the complex and potentially confusing paradigms they used, and does not reflect a general lack of understanding regarding defaults. Using simple scenarios, Experiments 1A and 1B provide clear evidence that people can optimally set defaults given their goals. In Experiment 2, we conducted a direct and conceptual replication of one of Zlatev et al.'s original studies, which found that participants selected the optimal default significantly less than chance. While our direct replication found results similar to those in the original study, our conceptual replication, which simplified the task, instead found the opposite. Experiment 3 manipulated the framing of the option attributes, which were confounded with the default in the original study, and found that the original framing led to below-chance performance while the alternate framing led to above-chance performance. Together, our results cast doubt on the prevalence and generalizability of default neglect, and instead suggest that people are capable of setting optimal defaults in attempts at social influence.

Exploiting asymmetric signals from choices through default selection.

Setting defaults is an effective nudge, but few studies have examined situations where individuals can select their own default settings. Past research suggests that even when the final outcome is identical, observers perceive stronger signals from choices that switch from, rather than stay with, the default. In five experiments using hypothetical scenarios and an incentivized economic game, we test whether decision-makers driven by image concerns could strategically exploit that asymmetric signal. We found that in the presence of observers, participants were more likely to self-select into defaults that require them to switch to enhance a positive signal and into defaults that require them to stay to attenuate a negative signal. Our results support the framework of choice architecture as an implicit social interaction, and have potential implications for behavioral interventions in real-world settings.

Illusory inconsistencies in judgment: Stimulus-evoked reference sets and between-subjects designs.

Asked to judge the subjective size of numbers in a between-subjects design, participants rated 9 as larger than 221 (Birnbaum, 1999). The 9 > 221 effect seems to indicate that different stimuli evoke different contexts for comparison, and sounds a warning for the interpretation of between-subjects comparisons. We show that, contrary to appearances, the effect is not a result of stimulus-evoked reference sets. Instead, it is an artifact of the original 1-10 response scale and task instructions, which encourage a conflation of the response scale and the reference set. When ratings are expressed on a 1-1000 scale, or on a non-numerical slider scale, the effect reverses. However, we also show that stimuli can evoke their own comparative contexts, generating illusions of inconsistency in between-subjects designs. We report two novel findings - a 9 > 009 effect and a -2 > 2 effect - which are best explained by stimulus-evoked reference sets. Thus, while revealing that the 9 > 221 effect is an artifact of the original response scale, our study ultimately affirms Birnbaum's warning about the comparison of between-subjects ratings.