Determining social mechanisms for sequential decision-making in a virtual pedestrian route choice experiment

TL;DR

The paper investigates how social information drives sequential route-choice decisions in a virtual evacuation task. It tests whether people weight the most recent decisions more heavily or follow the overall majority by presenting four social-sequence scenarios and two videos, and it compares three candidate decision rules using a probabilistic framework $P_A = \frac{1}{1+ a s^{-I}}$ with parameters $a$, $s$, and strategy-dependent $I$. Across 382 participants, the majority-following rule best explains the data (via AIC) and self-reported strategies largely corroborate this, with recency effects being weak or absent; gender differences emerge in specific scenarios. These findings illuminate human social-sequential decision-making and provide empirical grounding for incorporating majority-based social mechanisms into pedestrian movement models, while highlighting the need for broader, more ecologically valid tests. The results have practical relevance for evacuation modelling and crowd-management strategies under dynamic social influence, and point to further exploration of memory, bias, and context in shaping social decisions.

Abstract

Moving groups are routinely faced with a choice of different routes as part of their daily lives, such as choosing between exits from a building. Differences in moving speeds and environmental constraints often lead to individuals being able to observe the choices of others ahead. This social information can inform their decision-making, but exactly how this is being used remains an open question. Previous theoretical studies on animal groups have demonstrated that simple heuristics are plausible and accurate mechanisms, with some further predicting that more recent decisions are more heavily weighted. Experiments with fish corroborate the importance of more recent decisions; however, experimental work is limited. Here, we conduct an online survey with human participants to identify which social decision-making mechanism individuals follow. Contrary to previous experimental work, we find little indication that recent decisions are weighted more heavily; instead, our results suggest that following the majority of previous decisions is the dominant behaviour. Furthermore, self-reported decision-making mechanisms correlate with our experimental findings despite their variability, suggesting that on average individuals can recognize their behavioural tendencies. Our findings give insight into social sequential decision-making, and provide an empirical foundation for integrating realistic social decision mechanisms into pedestrian movement models.

Figures (6)

• Figure 1: Screenshot of the virtual environment as seen by the participants.
• Figure 2: The experimentally determined probability of choosing route A in the four scenarios, centred at $0.5$. The asterisks at the end of the bars indicate a value of p-value $<0.01$ from a binomial test for the null hypothesis that $P(A)=0.5$. Error bars show 95% confidence intervals. The number of participants for each scenario were: 99 (AAA); 97 (AAB); 90 (ABA); 96 (ABB).
• Figure 3: Distribution of self-reported strategies in route choice based on a manual classification (a), and simplified classification of two categories used in the analysts (b). See text for a more detailed description of the strategy classes.
• Figure 4: The proportion of participants choosing route A, P(A), for the different scenarios. We show P(A) for our experimental data (compare to Figure \ref{['fig:bplot1']}) and the fitted values for the three different theoretical models for decision-making strategies introduced in the text. The offset along the x-axis is for clarity of illustration.
• Figure A.1: Age distribution of participants. The median age was 27 years all, with most participants falling into the range between 18-34 and a few outliers over 50. Consequently the age of the participants is not informative enough to be considered as a factor in decision-making in this context.