In simple judgment tasks, it is generally assumed that thinking for longer leads to more accurate judgments, providing better benefits as suggested by the speed-accuracy tradeoff framework. However, human cognitive resources are limited, and longer thinking induces cognitive costs such as subjective workload. Therefore, a total benefit should be considered under the tradeoff between thinking benefits (i.e., improving accuracy) and thinking costs (i.e., increasing cognitive load) as suggested by the resource rationality framework. We examined this issue using computer simulations and behavioral experiments. Our simulations showed that, if a thinking cost was introduced based on resource-rational approaches, there was an optimal length of time for maximizing a total benefit and the total benefit gradually decreased there. In addition, our experiments demonstrated that judgment accuracy did not always improve even if participants were provided a longer thinking time; conversely, longer thinking time was likely to increase their subjective workload. These results are consistent with resource rationality rather than speed-accuracy tradeoff. The importance of considering cognitive load is suggested to further understand human intelligence in the context of a speed-accuracy tradeoff.

We propose a method to use anchor-biased numerical estimates to enhance the wisdom of the crowd (i.e., aggregating individual estimates becomes more accurate). We predicted that better wisdom of crowds could be achieved by combining estimates affected by two sufficiently different anchors. We conducted a behavioral experiment on anchoring effects and computer simulations of the wisdom of crowds. The behavioral experiment revealed that anchor-biased estimates did not always produce larger errors but produced more accurate or less accurate estimates depending on the relationship between the anchor and true values. We also found that even in the absence of anchoring effects, the estimates were biased. The results of computer simulations revealed that robust and better wisdom of crowds could be achieved using the proposed method. Contrastingly, aggregating estimates that were not biased by anchors did not always lead to better wisdom of crowds.

It is generally difficult for people to make rational and accurate judgments under their limited cognitive resources. In this study, we propose an intervention to easily improve people’s judgmental accuracy with less workload by waiting for a short time at the beginning of a task. By using a simple binary choice task, we found that when a short (1s) waiting time was inserted, participants showed higher accuracy than when no waiting time was inserted, and they felt less mental workload than when a longer (2.5s) waiting time was inserted. To examine the underlying implicit cognitive processes, we applied mouse tracking approaches during choice behaviors. We found that the inserted time enhanced participants’ change of mind (i.e., they amended their initial wrong judgments). These results suggest that making people wait for only 1s will serve as a simple, effective, and resource-rational intervention to boost people’s accuracy of judgments. Because of its simplicity, we believe that this intervention has potential to be applied in various fields.

Recently, nudging approaches wherein peoples decisions are altered in a predictable direction have attracted attention.Conversely, many embodied cognition approaches that relate peoples mind with their body have been studied in cognitivescience. Based on these approaches, we investigated whether a forward posture (defined by leaning forward in a chair)generated by the environment can enhance a particular decision. We also evaluated the types of decisions that are likelyto be enhanced by the forward posture. Behavioral experiments via a forward or normal chair where the seat allows littleor no lean revealed that a forward posture can affect the decision making, particularly participants willingness to changetheir own attitude. We discuss the possible applications of leading predictable decisions from the environment and settingthe decision environment in the real world.

Human memory has various deficits such as forgetting. Such deficits are generally regarded as human irrationality. However, superficial deficits in human cognition can be understood differently as rational aspects in terms of the interaction between human cognition and the environmental feature. Based on this idea, the present study analyzed the nature of memory-based judgment errors. We hypothesized that systematic errors are produced when ecologically rational inferences based on statistical regularity in the environment are performed in uncertain situations. To verify this hypothesis, we proposed a benchmark for a rational inference model of memory-based judgments under uncertainty, and tested it by analyzing real-world data, computer simulations, and a behavioral experiment. We found that the error patterns participants showed in the memory-based judgment were consistent with those predicted by the rational inference benchmark. These findings provide new insights into the errors produced by memory-based judgments from the rational side of cognition.

Previous studies have shown that individuals often make inferences based on heuristics using recognition, fluency, or familiarity. In the present study, we propose a new heuristic called familiarity-matching, which predicts that when a decision maker is familiar (or unfamiliar) with an object in a question sentence, s/he will choose the more (or less) familiar object from the two alternatives. We examined inference processes and ecological rationality regarding familiarity-matching through three studies including behavioral experiments and ecological analyses. Results showed that participants often used familiarity- matching in solving difficult binary choice problems, and that familiarity-matching could be applied in an ecologically rational manner in real-world situations. A new perspective on human cognitive processes is discussed in this study.

Previous studies have shown that when choosing one of thelogically equivalent frames (e.g., “half full” or “half empty”),speakers tend to choose one based on a reference point. Forexample, when the amount of water in a glass with 500ml ca-pacity was originally 0ml (or 500ml) and then increased (ordecreased) to 250ml, speakers tended to express the contentof water in the glass as “half full” (or “half empty”). We ex-amined why speakers chose one of the logically equivalentframes. In addition, we examined whether an irrelevant refer-ence point affected speakers’ choice of frame. In order to ex-amine these two issues, we conducted three behavioral exper-iments using a frame choice task. Specifically, participantswere presented with a task-relevant (story-based) or task-irrelevant (prime-based) reference point and then asked tochoose a frame. Following this, they were asked to reveal thereason for the frame choice. Our findings were summarizedwith the following two points. First, when reference pointswere task-relevant, many participants chose a frame based onthe reference point with explicit reason. Second, even whenreference points were task-irrelevant, they affected framechoices and almost all of our participants did not report the ef-fect of the irrelevant reference point. These results indicatethat the effect of reference points on frame choices is robustand that people do not always notice the effect.

Making rational judgments is not always easy. Given that aggregation of the distributed labor force through Internet has become common, a simple and cost-effective solution is needed to improve worker performance. We tested the hypothesis that enforcing a certain decision time boosts job performance by not allowing workers to provide answers within a certain short time after presenting the task. We used the binary judgment tasks, and job performance with various enforced decision times were compared. Two behavioral experiments with physicians (N = 628) demonstrated that job performance was improved by enforcing a one-second decision time; this did not affect the cognitive load of physicians. Furthermore, it was suggested that adding a one-second decision time induced the optimal trade-off between the worker’s performance and cognitive load. Our results show that focusing on resource rationality could lead to simple and cost-effective solutions to real-world problems by boosting workers’ job performance.