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1. Implications of Context Effects in Consumer Utility Models for Optimal Product Design and Differentiation

   https://doi.org/10.1115/1.4065478  

   Gowharji, Waleed F; Michalek, Jeremy J; Whitefoot, Kate S (September 2024, Journal of Mechanical Design)

   Abstract Consumer choice models used in optimal product design typically ignore potential context effects by assuming the utility of each product is independent of the attributes of other products in the choice set. We characterize implications of context effects for profit-maximizing designs by deriving the first-order conditions of the design problem under alternative utility formulations, and we propose a utility function that incorporates context effects and has well-defined optimal design solutions for all products in the choice set. We then conduct a discrete choice survey experiment of automobile options and find statistically significant context-effect parameters and superior out-of-sample prediction when context-effect parameters are used in both logit and mixed logit models. These results suggest that context effects can be important in engineering design contexts and have the potential to affect optimal design differentiation. 

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2. High among‐species variability in the context dependence of herbivory across disturbance, weather and topoedaphic gradients

   https://doi.org/10.1111/1365-2745.14390  

   Sutton, Alex O; Ratajczak, Zak; Louthan, Allison M (October 2024, Journal of Ecology)

   Abstract Species interaction effects on populations can vary in both magnitude (i.e. strong vs. weak) and sign (positive, negative, or no effect). Context‐dependent effects of species interactions occur when the sign or strength of the interaction's effect on population growth rate changes across abiotic gradients.We know that species can vary substantially in the degree of context dependence they exhibit, even across similar abiotic gradients. However, few studies have characterised context dependence of co‐occurring species, limiting our ability to understand the implications of context dependence for species interaction effects on community composition.Using over three decades of data collected for 13 tallgrass prairie forbs at the Konza Prairie Biological Station, we parameterise density structured population models that predict population dynamics as functions of abiotic conditions and bison herbivory. We use these models to estimate the degree of context dependence in responses to bison herbivory for 13 species across three abiotic gradients: weather, fire frequency and soil type.All species showed significant context dependence for fire frequency in the same direction, though with variable magnitude, such that herbivory increased cover with more frequent fires. Context dependence with weather and soil type varied dramatically across species in both direction and magnitude. For example, herbivory effects on 3/13 species were stronger in wet conditions, but herbivory effects on 5/13 species were stronger in dry conditions. Thus, context dependence exhibited by individual species, as opposed to effects of abiotic conditions on the relative abundances of species, could generate much of the weather‐dependent effects of herbivory on community composition.Synthesis: Our work suggests that species can vary dramatically in the presence, direction and magnitude of context dependence, even when occurring in the same community and when considering the same species interaction (i.e. response to a herbivore). In addition, we find that context dependence could drive substantial variation in the effect of species interactions on community characteristics (e.g. composition) across multiple abiotic gradients. 

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3. Context dependence in the symbiosis between Dictyostelium discoideum and Paraburkholderia

   https://doi.org/10.1002/evl3.281  

   Scott, Trey J.; Queller, David C.; Strassmann, Joan E. (June 2022, Evolution Letters)

   Abstract Symbiotic interactions change with environmental context. Measuring these context-dependent effects in hosts and symbionts is critical to determining the nature of symbiotic interactions. We investigated context dependence in the symbiosis between social amoeba hosts and their inedible Paraburkholderia bacterial symbionts, where the context is the abundance of host food bacteria. Paraburkholderia have been shown to harm hosts dispersed to food-rich environments, but aid hosts dispersed to food-poor environments by allowing hosts to carry food bacteria. Through measuring symbiont density and host spore production, we show that this food context matters in three other ways. First, it matters for symbionts, who suffer a greater cost from competition with food bacteria in the food-rich context. Second, it matters for host-symbiont conflict, changing how symbiont density negatively impacts host spore production. Third, data-based simulations show that symbiosis often provides a long-term fitness advantage for hosts after rounds of growth and dispersal in variable food contexts, especially when conditions are harsh with little food. These results show how food context can have many consequences for the Dictyostelium-Paraburkholderia symbiosis and that both sides can frequently benefit. 

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4. Distinct neural mechanisms for heading retrieval and context recognition in the hippocampus during spatial reorientation

   https://doi.org/10.1038/s41467-024-50112-7  

   Gagliardi, Celia_M; Normandin, Marc_E; Keinath, Alexandra_T; Julian, Joshua_B; Lopez, Matthew_R; Ramos-Alvarez, Manuel-Miguel; Epstein, Russell_A; Muzzio, Isabel_A (July 2024, Nature Communications)

   Abstract Reorientation, the process of regaining one’s bearings after becoming lost, requires identification of a spatial context (context recognition) and recovery of facing direction within that context (heading retrieval). We previously showed that these processes rely on the use of features and geometry, respectively. Here, we examine reorientation behavior in a task that creates contextual ambiguity over a long timescale to demonstrate that male mice learn to combine both featural and geometric cues to recover heading. At the neural level, most CA1 neurons persistently align to geometry, and this alignment predicts heading behavior. However, a small subset of cells remaps coherently in a context-sensitive manner, which serves to predict context. Efficient heading retrieval and context recognition correlate with rate changes reflecting integration of featural and geometric information in the active ensemble. These data illustrate how context recognition and heading retrieval are coded in CA1 and how these processes change with experience. 

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5. Valuations of target items are drawn towards unavailable decoy items due to prior expectations

   https://doi.org/10.1093/pnasnexus/pgae232  

   Izakson, Liz; Yoo, Minhee; Hakim, Adam; Krajbich, Ian; Webb, Ryan; Levy, Dino_J; Tserenjigmid, ed., Gerelt (June 2024, PNAS Nexus)

   Abstract When people make choices, the items they consider are often embedded in a context (of other items). How this context affects the valuation of the specific item is an important question. High-value context might make items appear less attractive because of contrast—the tendency to normalize perception of an object relative to its background—or more attractive because of assimilation—the tendency to group objects together. Alternatively, a high-value context might increase prior expectations about the item's value. Here, we investigated these possibilities. We examined how unavailable context items affect choices between two target items, as well as the willingness-to-pay for single targets. Participants viewed sets of three items for several seconds before the target(s) were highlighted. In both tasks, we found a significant assimilation-like effect where participants were more likely to choose or place a higher value on a target when it was surrounded by higher-value context. However, these context effects were only significant for participants’ fastest choices. Using variants of a drift-diffusion model, we established that the unavailable context shifted participants’ prior expectations towards the average values of the sets but had an inconclusive effect on their evaluations of the targets during the decision (i.e. drift rates). In summary, we find that people use context to inform their initial valuations. This can improve efficiency by allowing people to get a head start on their decision. However, it also means that the valuation of an item can change depending on the context. 

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