What's not to like about Likert? Developing a nonverbal animal preference scale (NAPS)

Abstract

Rating scales, such as Likert scales, are incredibly flexible and intuitive tools for measuring individuals' rating of agreement with or relative preference for many types of stimuli. For humans, this typically involves ratings of agreement between end points representing distinct attitudes or beliefs; For example, strongly disagree to strongly agree. Nonverbal versions of Likert scales have also been presented to children, allowing them to indicate their degree of preference, pain, or happiness.However, before the current study, no known efforts had been made to develop a nonverbal rating scale for use with nonhuman animals. Such a scale would be a useful welfare tool, allowing nonverbal individuals to indicate not just relative preferences between pairs of items but their degree of liking for individual items. I present an outline of the steps taken to create such a scale for use with three zoohoused gorillas. Two gorillas succeeded in associating preferred and less preferred foods with different response buttons but none of the gorillas were able to effectively use the neutral response button. It is possible that limits in gorillas' capacity for conditional discriminations and/or conceptualization of constructs as abstract as "liking" impeded training. These data are relevant for understanding gorilla cognition and can inform continued efforts to create a tool for nonhumans to communicate their preferences to human caregivers in a more nuanced way than is currently possible.

A Food for All Seasons: Stability of Food Preferences in Gorillas across Testing Methods and Seasons

“…Assessing the total proportion of trials chosen out of all of the trials offered accounted for the noise and variance in the particular food that the target food was paired with to the best of our ability given the manner in which the data were collected. These limitations arose in part because this study was designed to provide information about a range of preferred and less preferred foods for use in a Likert scale training procedure [24]. For that study, we needed a gage of preference for a larger set of items.…”

“…Testing took place in a restricted access indoor area, with each gorilla tested in an individual holding area where they spent approximately an hour every morning for feeding and training while their primary habitats were being serviced. During this period, the gorillas also participated in other tasks including various two alternative forced-choice tasks [48], matching-to-sample training [49], cognitive bias tests [30,50,51], and a conditional discrimination task [24] all presented on a touchscreen.…”

“…Although touchscreen methods for assessing preferences have the advantage of allowing for the presentation of items that may not be available at the time of testing [10,24], they require validation to demonstrate that subjects perceive the images as representing the actual items depicted. Tests have revealed mixed evidence for picture-object correspondence in various species including primates [25].…”

Primatology in zoos: Studying behavior, cognition, and welfare

“…Moreover, zoos from America (e.g., Martin & Shumaker, 2022;Vonk, 2022), Europe (e.g., Laméris et al, 2022;Spiezio et al, undefined 2022), and Asia (e.g., Yamanashi et al, 2022) are represented, reflecting the global interest in zoo-based primatological research (Hopper, 2017).…”

“…for this special issue I wanted to invite contributions from researchers studying zoo-housed monkeys and prosimians (e.g., Cairo-Evans et al, 2022;Hayden et al, 2022;Spiezio et al, 2022) in addition to those studying apes (e.g., Laméris et al, 2022;Martin & Shumaker, 2022;Motes-Rodrigo & Tennie, 2022;Vonk, 2022;Yamanashi et al, 2022).…”