Choice overload and its consequences for decision making in animals

The National Science Foundation Division of Environmental Biology awarded the University of Tennessee $1.206 million on October 1, 2026, under the Biological Sciences program (CFDA 47.074) to investigate choice overload in animal decision-making and its consequences for survival and reproduction.

The research examines why animals sometimes make poor decisions when faced with too many options or excessive decision complexity. Researchers will experimentally study choice overload in two biological contexts: bumblebees making foraging decisions and crickets making mating decisions. The work will identify which features of animal choices—including decision task difficulty, assortment complexity, and preference uncertainty—make choice overload more likely. The project also supports public education through design and development of a video game exploring choice overload, which will anchor an outreach program serving East Tennessee high schools.

Performance occurs in Knoxville, Tennessee, with a period of performance from October 1, 2026, through September 30, 2029. The funding mechanism is a Project Grant to the University of Tennessee System Office.

Abstract

Animals routinely make decisions that affect whether they survive and reproduce, yet they frequently do not choose the best options. ?rational? Decision making occurs when animals act to achieve the best result, while irrational decisions fail to do so. Which result is the best is often measured in terms of fitness. Scientists do not fully understand why animals sometimes make poor decisions, and how changes in their decision making affect their success. This project investigates one cause of irrational decision making, choice overload. Choice overload happens when individuals have too many options or face a decision that is too complex. As a result, decision makers might choose inferior options, take longer to decide, or fail to decide at all. The researchers will experimentally study this problem in two situations: bumblebees making foraging decisions and crickets making mating decisions. The goal is to find out which features of animal choices make choice overload more likely. This project will uncover how animals make decisions when they must consider a lot of information. In addition to promoting the progress of science, this project will support public education. The researchers will design and build a video game exploring choice overload. The game will be the centerpiece of an outreach program that supports science education in east tennessee high schools. Irrational decisions, driven by choice overload, can negatively impact organismal fitness. Here, researchers will investigate three major factors hypothesized to drive choice overload: decision task difficulty, assortment complexity, and preference uncertainty arising from conflicting signal attributes or uncertainty in estimating the value of an attribute. In both bumblebees and field crickets, researchers will manipulate biologically relevant stimuli and quantify standardized measures of choice behavior to test how these potential drivers of choice overload influence decision outcomes. Choice overload is typically measured by its symptoms, which include changes in option selection, increased probability of choice deferral, and longer decision latencies. Researchers will systematically increase the number of distractors to determine whether the symptoms of choice overload worsen with assortment size. If choice overload predictably causes suboptimal decision making in animals, then signalers may attempt to exploit irrationality in receiver decision making. This project will provide a general framework for understanding when and why decision-making breaks down. Changes in decision making have broader implications for behavioral ecology and the evolution of communication and decision-making strategies, including changes in the strength and shape of selection imposed on signals and signalers by receivers and altered relationships between pollinators and their plant mutualists. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the foundation's intellectual merit and broader impacts review criteria.- subawards are not planned for this award.