​​​Limits of the social-benefit motive among high-risk patients:

A field experiment on influenza vaccination behaviour

Ozan Isler, Burcu Isler,Orestis Kopsacheilis Eamonn Ferguson 

(2020) BMC Public Health, 20(240) https://doi.org/10.1186/s12889-020-8246-3

Background. Influenza vaccine uptake remains low worldwide, inflicting substantial costs to public health. Messages promoting social welfare have been shown to increase vaccination intentions, and it has been recommended that health professionals communicate the socially beneficial aspects of vaccination. We provide the first test whether this prosocial vaccination hypothesis applies to actual vaccination behaviour of high-risk patients. Methods. In a field experiment at a tertiary care public hospital in Istanbul, Turkey, we compare the effects of two motivational messages for promoting vaccination. Using a between-subjects single-blind experimental design patients were randomly assigned to frames emphasizing the vaccine’s benefits to self (n = 125) or social benefits (n = 119). Free influenza vaccination was offered to each patient. Results. Among 222 patients who were not vaccinated for the season prior to the study (72% medically assessed to be at high risk), 42% in the self-benefit frame chose to receive a vaccination compared with 34% in the social-benefits frame, but the difference was not statistically significant (aOR = 1.63, 95% CI 0.90 to 2.95, p = 0.108). Reasons for vaccination focused primarily self-benefit (67%) rather than social-benefit (5%). Exploratory analysis showed that the effect of messages depended on patient perception of risk group membership (aORHigh / aORLow = 5.59, 95% CI 1.30 to 24.05, p = 0.021). In particular, emphasis on self-benefit was more influential among patients who perceived themselves to be in the risk group (aOR = 6.22, 95% CI 1.69 to 22.88, p = 0.006). Conclusions. In contrast to the literature observing intentions of low-risk populations, we found no evidence that social-benefit motivates actual vaccination behaviour among a high-risk patient population. Instead, those who self-categorize as being in the high risk group are more motivated by the self-benefit message.  Our results suggest that a stratified approach can improve coverage: even if an emphasis on social-benefit could be effective among low-risk groups, an emphasis on self-benefit holds more promise for increasing vaccination in medical organizational settings where high-risk groups are prevalent. Trial Registration. ClinicalTrials.gov NCT04230343 Retrospectively registered on the 13th January 2020. 


Reflection increases belief in God through self-questioning among non-believers

Onurcan Yilmaz & Ozan Isler  ​

(2019) Judgment and Decision Making​, 14(6), 649-657. https://journal.sjdm.org/19/190605/jdm190605.pdf

The dual-process model of the mind predicts that religious belief will be stronger for intuitive decisions, whereas reflective thinking will lead to religious disbelief (i.e., the intuitive religious belief hypothesis). While early research found intuition to promote and reflection to weaken belief in God, more recent attempts found no evidence for the intuitive religious belief hypothesis. Many of the previous studies are underpowered to detect small effects, and it is not clear whether the cognitive process manipulations used in these failed attempts worked as intended. We investigated the influence of intuitive and reflective thought on belief in God in two large-scale preregistered experiments (N = 1,602), using well-established cognitive manipulations (i.e., time-pressure with incentives for compliance) and alternative elicitation methods (between and withinsubject designs). Against our initial hypothesis based on the literature, the experiments provide first suggestive then confirmatory evidence for the reflective religious belief hypothesis. Exploratory examination of the data suggests that reflection increases doubts about beliefs held regarding God’s existence. Reflective doubt exists primarily among non-believers, resulting in an overall increase in belief in God when deciding reflectively.


Dr. Ozan Isler

Experimental and Behavioral Economist

Selected Publications

​​​Activating reflective thinking with decision justification and debiasing training

Ozan Isler, ​Onurcan Yilmaz & Burak Dogruyol  

(2020) Judgment and Decision Making​, 15(6), 926-938. http://journal.sjdm.org/20/201008/jdm201008.pdf

Manipulations for activating reflective thinking, although regularly used in the literature, have not previously been systematically compared. There are growing concerns about the effectiveness of these methods as well as increasing demand for them. Here, we study five promising reflection manipulations using an objective performance measure—the Cognitive Reflection Test 2 (CRT-2). In our large-scale preregistered online experiment (N = 1,748), we compared a passive and an active control condition with time delay, memory recall, decision justification, reflection training, and combination of reflection training and decision justification. We found no evidence that online versions of the two regularly used reflection conditions—time delay and memory recall—improve cognitive performance. Instead, our study isolated two less familiar methods that can effectively and rapidly activate reflective thinking: (1) a brief reflection training, designed to counter common cognitive biases, and (2) simply asking participants to justify their decisions. 


Is intuition really cooperative? Improved tests support the social heuristics hypothesis 

Ozan Isler, ​John Maule & Chris Starmer

(2018) PLoS ONE 13(1): e0190560. https://doi.org/10.1371/journal.pone.0190560

Understanding human cooperation is a major scientific challenge. While cooperation is typically explained with reference to individual preferences, a recent cognitive process view hypothesized that cooperation is regulated by socially acquired heuristics. Evidence for the social heuristics hypothesis rests on experiments showing that time-pressure promotes cooperation, a result that can be interpreted as demonstrating that intuition promotes cooperation. This interpretation, however, is highly contested because of two potential confounds. First, in pivotal studies compliance with time-limits is low and, crucially, evidence shows intuitive cooperation only when noncompliant participants are excluded. The inconsistency of test results has led to the currently unresolved controversy regarding whether or not noncompliant subjects should be included in the analysis. Second, many studies show high levels of social dilemma misunderstanding, leading to speculation that asymmetries in understanding might explain patterns that are otherwise interpreted as intuitive cooperation. We present evidence from an experiment that employs an improved time-pressure protocol with new features designed to induce high levels of compliance and clear tests of understanding. Our study resolves the noncompliance issue, shows that misunderstanding does not confound tests of intuitive cooperation, and provides the first independent experimental evidence for intuitive cooperation in a social dilemma using time-pressure.


​​​Religion, parochialism and intuitive cooperation

Ozan Isler, Onurcan Yilmaz & John Maule

(2021) Nature Human Behaviour. https://doi.org/10.1038/s41562-020-01014-3 (open-access link)

Religions promote cooperation but they can also be divisive. Is religious cooperation intuitively parochial against atheists? Evidence supporting the social heuristics hypothesis (SHH) suggests that cooperation is intuitive independent of religious group identity. We test this prediction in a one-shot prisoner’s dilemma game, where 1,280 practicing Christian believers are paired either with a coreligionist or an atheist and where time-limits are used to increase reliance on either intuitive or deliberated decisions. We explored another dual-process account of cooperation, the self-control account (SCA), which suggests that visceral reactions tend to be selfish and that cooperation requires deliberation. We found evidence for religious parochialism but no support for SHH’s prediction of intuitive cooperation. Consistent with SCA but requiring confirmation in future studies, exploratory analyses showed that religious parochialism involves decision conflict and concern for strong reciprocity and that deliberation promotes cooperation independent of religious group identity.



Are we at all liberal at heart?

High-powered tests find no effect of intuitive thinking on moral foundations

Ozan Isler, Onurcan Yilmaz Burak Dogruyol 

(2021) Journal of Experimental Social Psychology, 92(104050) https://doi.org/10.1016/j.jesp.2020.104050

Two opposing views define the debate on the moral principles underlying human behavior. One side argues a central role for five moral foundations (care, fairness, loyalty, authority, sanctity), while the other argues that two of these (care, fairness) capture the essence of human moral concerns. In an experiment comparing these two views, Wright and Baril (2011) found that conservatives under cognitive load devalue loyalty, authority and sanctity, and become more liberal. Their finding of common intuitive concern with care and fairness supports the two-foundation perspective. In two high-powered preregistered experiments (N = 3275), we used time-pressure to induce intuitive thinking and tested Wright and Baril's finding that “we are all liberals at heart.” Although the manipulations worked as intended, Study 1 failed to identify an effect on the moral foundations questionnaire (MFQ). We conjectured that familiarity with standard survey items may weaken intuition manipulations by eliciting stable opinions. In Study 2, we therefore used not only the MFQ but also novel moral foundations vignettes. Study 2 failed to find an effect of time-pressure on either questionnaire type. An internal Bayesian meta-analysis indicated strong evidence against an effect of intuitive thinking on moral foundations.