中国科学院行为科学重点实验室知识库

风险决策和跨期决策与人类生存发展密切相关, 且两类决策在理论发展、行为效应及神经基础等方面具有相似性。为检验二者是否具有共同过程机制, 本研究以风险决策中的确定效应和跨期决策中的即刻效应为例, 采用眼动追踪技术比较了它们的局部、整体过程及模型拟合。辅以贝叶斯因子分析实验数据表明：二者的主要过程特征均相似, 且更符合非折扣模型假设; 二者在加工复杂程度等少数特征上有所不同; 确定和即刻信息在加工方向等特征上存在特异性。这表明二者可能具有共同的核心决策规则：两类决策更可能遵循非折扣模型预期的简捷、启发式规则, 而不是折扣模型所假设的补偿性、基于选项规则。本研究为建立两类决策的共同解释框架做出了有益尝试, 并为决策比较研究方法提供新的方向。

Risky choice (RC) and intertemporal choice (IC) are two types of common decisions that are vital to human’s everyday life. RC and IC share similarities regarding theoretical development, behavioral effects, and neural basis. One critical challenge is that, although previous studies have revealed that RC and IC involve similar cognitive processes, results are mixed regarding what the exact mechanism might be. The mainstream discounting model hypothesizes that both RC and IC follow a compensatoryand alternative-based rule. However, other models suggest that RC and IC commonly involve non-compensatory and attribute-based processing. Moreover, prior studies primarily based their findings on outcome data and few have attempted to determine whether RC and IC shared a common decision process at the cognitive computational level. 
To fill this gap, the present study adopts a systematic approach to disentangle the exact mechanism of RC and IC. We considered two well-studied behavioral effects, namely, certainty effect of RC and immediacy effect of IC, respectively, and compared their underlying local and holistic process characteristics by using eye-tracking technique. Besides, we employed hierarchical Bayesian modeling to assess whether alternative- or attribute-based models better fit both RC and IC. We designed a 2×2 within-subject paradigm, with the choice task (RC vs. IC) and the construct of decision options (with vs. without certain/immediate option) as factors. Thirty-three postgraduate students participated in our study. As we were particularly interested in two pairs of decision rules, i.e., compensatory/non-compensatory rules and alternative-based/attribute-based rules, we included a series of decision attributes that reflected them, based on the local and holistic process characteristics derived from eye-movement data to test our hypotheses. 
Our entire set of analyses aimed to (1) determine whether the decision processes of RC and IC are similar and (2) identify the best computational model that is more suitable for both decisions. For the first aim, results show that RC and IC indeed share comparable decision processes, albeit having a few differences in other aspects. Specifically, RC and IC differ in process characteristics, such as complexity and holistic eye-movement dynamics, and IC is processed in a relatively more deliberate, deeper fashion than RC. However, they are similar in other characteristics, such as search direction, which is more relevant to making decisions. For the second aim, computational modeling of process characteristics suggests that both types of decisions are consistent with non-discounting models. In particular, results of search direction, in light of Bayesian model comparison, reveals that participants are more likely to follow the non-compensatory, attribute-based rule rather than the alternative-based/attribute-based rule when deciding for both RC and IC. Furthermore, different task constructs of decision options, i.e., with or without certain/immediate option, show distinct process characteristics, such as direction, complexity, and depth in both RC and IC.
To conclude, the present study shows that although differences exist between RC and IC, they indeed have shared cognitive mechanisms at the core of the decision processes. In both types of decisions, contrary to classic discounting models, individuals seem not to follow compensatory, attribute-based rules, which undergoes a “weighting and summing” or “delay discounting” process. Instead, they are more likely to use simple heuristic rules hypothesized by non-discounting models. Moreover, when including certain or immediate options, individuals tend to follow less compensatory and non-dominant (neither attribute-based nor alternative-based) rules. In sum, our findings not only provide a theoretical and empirical basis for the establishment of a common framework for RC and IC, but also provide a novel direction for thorough theoretical and methodological comparisons between variant decision tasks.