Risky choice (RC) and intertemporal choice (IC) are common decisions we make in daily life, and these decisions are vital to the development of human beings. These two types of decisions are similar in terms of theoretical development, behavioral effects, and cognitive neural basis. The core similarity of the two is that they might involve similar process mechanisms. The mainstream discounting model holds that RC and IC are similar in that they follow a compensatory, alternative-based rule. However, other models suggest that RC and IC are similar in that their processing is non-compensatory and attribute-based. However, the previous research was based on evidence from outcome data and research that explore whether the two have a shared decision process are rare.
In this paper, in order to examine whether RC and IC involve similar decision process, by using the logic from “special” (based on effect) to “general” (based on equivalence conversion), and from “simple” (single outcome) to “complex” (double outcome), we utilized the eye tracking method to compare the underlying process in RC and IC. We adopted a series of new analytical methods, such as hierarchical Bayesian model fitting, Bayesian estimation, and scanpath analysis to compare behavioral characteristics, local process characteristics and holistic process characteristics of the two types of decisions. In detail, we focused on two decision factors: compensatory/non-compensatory rule, alternative based/attribute based rule. Based on the local and holistic process characteristics, we select a series of decision attributes that reflect the compensatory/non-compensatory rule, alternative based/attribute based rule, and use the eye-tracking indexes to test these decision attributes. By comparing the decision process the two, we futher determine which models are more suitable for these two decisions.
In study 1, considering the similar behavioral effects of RC and IC, we compared the process mechanisms of the special behavioral effects of RC and IC from a qualitive perspective. In this study, we compared the certainty effect of RC and the immediacy effect of IC (single-outcome block) and the "hidden zero" effect of RC and IC (double-outcome block). We found that although RC and IC differed in some process characteristics, such as complexity and holistic dynamic eye movement pattern, they are similar in other characteristics. In addition, except for local processing direction, other characteristics we examined suggested that the two types of decision are consistent with the assumptions of a non-discounting models, and their information processing were more likely to follow the non-compensatory, attribute-based rule.
In study 2, to overcome the disadvantages of the previous studies, which failed to control the confounding for results from parameter specificity and individual differences, we established a paradigm of probability and delay equivalence conversion to set “equivalent RC and IC options pairs,” and we compared the process mechanisms of the two in “general condition” from a quantitative perspective. Study 2 also consists of two sub-studies. We compared the underlying process in single-outcome (sub-study 3) and double-outcome (sub-study 4) blocks. We found that based on equivalence conversion, RC and IC showed different behavioral charactoristics. However, they were similar in terms of information processing, expectation for complexity, and holistic dynamic eye movement pattern. In addition, except for local processing direction, the other characteristics we examined suggested that the two types of decisions are consistent with the assumptions of a non-discounting model, and their information processing were more likely to follow a non-compensatory, attribute-based rule.
All of the studies presented in this paper showed that although differences exist between RC and IC in the details of few decision processes, such as in terms of compexity and holistic and dynamic eye movement pattern. However, at the core of the decision rule, RC and IC share cognitive mechanisms: In these two types of decisions, contrary to classical discounting models, people do not follow a compensatory, dimension-based rules and undergo a “weighting and summing” or “delay discounting” process to make a decision. However, they are likely to use simple heuristic rules that are expected by non-discounting models. This study provides a theoretical basis for the establishment of a common interpretation framework for RC and IC, as well as opens a new direction for the research methods and analytical methods for comparative research on different decision tasks.