Toward a coherent understanding of risky, intertemporal, and spatial choices：Evidence from eye-tracking and subjective evaluation

Abstract: The fundamental issue regarding the difference between humans and animals has puzzled researchers in a broad range of academic fields and specializations. The ability to trade, which symbolizes the progress of human civilization, may be regarded as an important distinction between humans and animals. To sustain a trading activity, people need to deal with the possible issues of long-distance delivery (spatial choice), delayed delivery (intertemporal choice), and unfulfilled delivery (risky choice) in the exchange of goods.

These choices of different domains were well represented by the tangible (outcome) and intangible (probability/time/space) dimensions. Normally, the family of compensatory rules assumes that choice should be reached by comparing options which have been converted into the same units of quantity (Overall Payoff _A vs. Overall Payoff _B) in a way of “translating intangible elements into tangible ones” algorithm. Whereas, the family of non-compensatory rules assumes that choice should be reached by directly comparing values measured using different units of quantity (?Outcome _{A, B} vs. ?Probability _{A, B} /?Delay _{A, B} /?Space _{A, B}) in a way of “pitting intangible elements against tangible ones” rule. To test whether human beings have the potential to deal with the intangible dimensions of the data, the present paper attempts to obtain evidence to support the “pitting intangible elements against tangible ones” rules from a variety of decision tasks, which were formed by combing both tangible and intangible dimensions.

Study 1 aims to examine whether outcome difference between options and the probability/time/space difference between options were directly compared in three choice domains by using the eye-tracking technique. Our findings show that, from the group-level, decision makers perform a consistent dimension-based search pattern in the three domains, indicating that the decision processes are more dependent on a way of intra-dimensional comparison. From the individual-level, the vast majority of participants were classified as decision makers who using dimension-based strategy. Moreover, the two index we constructed, difference in gaze duration and difference in saccades frequency, could significantly predict the behavioral choice shift. Those results provide supporting evidence for dimensioned-based strategy in three choice domains.

However, Study 1 is still unable to answer the further question of whether the final decisions are reached through a process of comparing the eye movement information of ?Outcome _A,B with ?Probability _A,B /?Delay _A,B /?Space _A,B . Study 2 therefore borrows a Visual Analog Scale to further examine whether the ?Outcome _A,B and ?Probability _A,B /?Delay _A,B /?Space _A,B were treated in an equate-to-differentiate way in reaching the final decisions in three domains. Our findings indicate that the decisions can be made by the way of “intra-dimensional difference evaluation” prescribed by equate-to-differentiate theory.

The current paper provides supportive evidence for the comparison rule of “pitting intangible elements against tangible ones” and break a new ground different from the “translating intangible elements into tangible ones” algorithm. Future studies may consider the development of a general model to explain the choices of three different domains.