Defining value through quantity and quality—Chimpanzees (Pan troglodytes) undervalue food quantities when items are broken

Abstract

Decision-making is largely influenced by the relative value of choice options, and the value of such options can be determined by a combination of different factors (e.g., the quantity, size, or quality of a stimulus). In this study, we examined the competing influences of quantity (i.e., the number of food items in a set) and quality (i.e., the original state of a food item) of choice items on chimpanzees’ food preferences in a two-option natural choice paradigm. In Experiment 1, chimpanzees chose between sets of food items that were either entirely whole or included items that were broken into pieces before being shown to the chimpanzees. Chimpanzees exhibited a consistent bias for whole food items even when such choice options consisted of a smaller overall quantity of food than the sets containing broken items. In Experiment 2, chimpanzees chose between sets of entirely whole food items and sets of initially whole items that were subsequently broken in view of the chimpanzees just before choice time. Chimpanzees continued to exhibit a bias for sets of whole items. In Experiment 3, chimpanzees chose between sets of new food items that were initially discrete but were subsequently transformed into a larger cohesive unit. Here, chimpanzees were biased to choose the discrete sets that retained their original qualitative state rather than towards the cohesive or clumped sets. These results demonstrate that beyond a food set’s quantity (i.e., the value dimension that accounts for maximization in terms of caloric intake), other seemingly non-relevant features (i.e., quality in terms of a sets original state) affect how chimpanzees assign value to their choice options.

Playing it safe? Solitary vervet monkeys (Chlorocebus pygerythrus) choose high‐quality foods more than those in competition

“…However, in Teichroeb and Aguado () the high‐quantity sites were perceptually very different from low‐quantity sites, being baited with six times the reward quantity. Food quantity is an extremely basic and salient factor relevant to survival, and a variety of species, from salamanders to elephants, have been found to be adept in quantity discrimination tasks (Parrish, Evans, & Beran, ). Visual cues in foraging may be even more important in catarrhine primates who possess enhanced visual abilities (e.g., trichromacy) relative to other sensory capabilities such as olfaction (Teichroeb & Kumpan, ).…”

Wanting, liking and welfare: The role of affective states in proximate control of behaviour in vertebrates

“…For example, reduction in uncertainty and ambivalence by exploration can be rewarding (Anselme, 2010;Franks, Champagne, & Higgins, 2013;Inglis, 2000). In addition, increasing quantity and numerosity may intensify reward (Parrish, Evans, & Beran, 2015;Petrazzini & Wynne, 2016). Moreover, actively dealing with a situation or exerting choice may increase a situation's attraction (Niv, Langdon, & Radulescu, 2015; e.g., contra-freeloading: Inglis, Forkman, & Lazarus, 1997;Ogura, 2011).…”

Quantity discrimination in angelfish, Pterophyllum scalare: a novel approach with food as the discriminant

“…Under this paradigm, subjects have to select between two visible, simultaneously presented, numerically different sets of food items, which generally remain in view at the time of choice. This spontaneous quantity discrimination has been employed in studies with mammals (Baker, Morath, Rodzon, & Jordan, 2012;Bánszegi, Urrutia, Szenczi, & Hudson, 2016;Beran, Evans, & Harris, 2008;Cox & Montrose, 2016;Hanus & Call, 2007;Miletto Petrazzini & Wynne, 2016;Parrish, Evans, & Beran, 2015) and birds (Bogale, Aoyama, & Sugita, 2014;Garland, Low, & Burns, 2012;, but it has also been utilized in other animal species such as amphibians (Krusche, Uller, & Dicke, 2010;Stancher, Rugani, Regolin, & Vallortigara, 2015;Uller, Jaeger, Guidry, & Martin, 2003) and reptiles (Miletto Petrazzini, Fraccaroli, Gariboldi, Agrillo, Bisazza, Bertolucci, & Foà, 2017).…”