The Impact of Experience on Preference Formation and Context Effects in Multi-alternative, Multi-attribute Choice

Within the domain of preferential choice, it has long been thought that context effects, such as the attraction and compromise effects, arise due to the constructive nature of preferences and thus should not emerge when preferences are stable. We examined this hypothesis with a series of experiments where participants had the opportunity to experience selected alternatives and develop more enduring preferences. Our results suggest that context effects can still emerge when stable preferences form through experience. This suggests that multi-alternative, multi-attribute decisions are likely influenced by relative evaluations, as hypothesized by many computational models of decision-making, even when participants have the opportunity to experience options and learn their preferences. In addition, the direction of observed context effects is opposite to standard effects and appears to be quite robust. Our post-hoc explorations suggest that the context effect reversals we observe may relate to the subjective representation of options.

Attention biases preferential choice by enhancing an option's value

Does attending to an option lead to liking it? Though attention induced valuation is often hypothesized, evidence for this causal link has remained elusive. We test this hypothesis across two studies by manipulating attention during a preferential decision and its perceptual analog. In a free-viewing task, we found attention biased choice and eye movement pattern in the preferential decision more than during the perceptual analog. In a controlled-viewing task, we again found attention had a larger effect on choice in the preferential decision than its perceptual analog. Computational modeling of the data reveals that attention impacted preference by discounting the unattended option’s value. These results support the attention-induced valuation hypothesis. We suggest that attention impacts preference via a normalization process where an option's representation is scaled by its spatial and temporal neighbors. Attention provides a gain modulation on this representation at the sensory and value processing levels.

Evaluation of the Saponin Content in Panax vietnamensis Acclimatized to Lam Dong Province by HPLC–UV/CAD

Panax vietnamensis, or Vietnamese ginseng (VG), an endemic Panax species in Vietnam, possesses a unique saponin profile and interesting biological activities. This plant is presently in danger of extinction due to over-exploitation, resulting in many preservation efforts towards the geographical acclimatization of VG. Yet, no information on the saponin content of the acclimatized VG, an important quality indicator, is available. Here, we analyzed the saponin content in the underground parts of two- to five-year-old VG plants acclimatized to Lam Dong province. Nine characteristic saponins, including notoginsenoside-R1, ginsenoside-Rg1, -Rb1, -Rd, majonoside-R1, -R2 vina-ginsenoside-R2, -R11, and pseudoginsenoside-RT4, were simultaneously determined by HPLC coupled with UV and with a charged aerosol detector (CAD). Analyzing the results illustrated that the detection of characteristic ocotillol-type saponins in VG by CAD presented a superior capacity compared with that of UV, thus implying a preferential choice of CAD for the analysis of VG. The quantitative results indicating the saponin content in the underground parts of VG showed an increasing tendency from two to five years old, with the root and the rhizome exhibiting different saponin accumulation patterns. This is the first study that reveals the preliminary success of VG acclimatization and thereby encourages the continuing efforts to develop this valuable saponin-rich plant.

Polarization and extremism emerge from rational choice: Estimation as a solution to biased sampling

Polarization is often described as the product of biased information search, motivated reasoning, or other psychological biases. However, polarization and extremism can still occur in the absence of any bias or irrational thinking. In this paper, we show that polarization occurs among groups of decision makers who are implementing rational choice strategies that maximize decision efficiency. This occurs because extreme information enables decision makers to make up their minds and stop considering new information, whereas moderate information is unlikely to trigger a decision and is thus under-represented in the information decision-makers collect. Furthermore, groups of decision makers will generate extremists -- individuals who hold strong views despite being uninformed and impulsive. In re-analyses of seven empirical studies spanning perceptual and preferential choice and a new study examining politically and affectively charged decisions, we show that both polarization and extremism manifest when decision makers gather information to make a choice. Polarization did not occur, however, when participants made an inference about the difference between two quantities as opposed to deciding which one is superior. Estimation therefore offers a theoretically-motivated intervention that can increase the amount of information people consider and reduce the degree of polarization and extremism among groups of individuals.