Motion Illusions as Environmental Enrichment for Zoo Animals: A Preliminary Investigation on Lions (Panthera leo)

Abstract

Investigating perceptual and cognitive abilities of zoo animals might help to improve their husbandry and enrich their daily life with new stimuli. Developing new environmental enrichment programs and devices is hence necessary to promote species-specific behaviors that need to be maintained in controlled environments. As far as we are aware, no study has ever tested the potential benefits of motion illusions as visual enrichment for zoo animals. Starting from a recent study showing that domestic cats are spontaneously attracted by a well-known motion illusion, the Rotating Snake (RS) illusion, we studied whether this illusion could be used as a visual enrichment for big cats. We observed the spontaneous behavior of three lionesses when three different visual stimuli were placed in their environment: the RS illusion and two control stimuli. The study involved two different periods: the baseline and the RS period, in which the visual stimuli were provided to the lionesses. To assess whether the lionesses were specifically attracted by the RS illusion, we collected data on the number of interactions with the stimuli, as well as on the total time spent interacting with them. To investigate the effect of the illusion on the animals’ welfare, individual and social behaviors were studied, and compared between the two periods. The results showed that two lionesses out of three interacted more with the RS stimulus than with the two control stimuli. The fact that the lionesses seemed to be more inclined to interact with the RS stimulus indirectly suggests the intriguing possibility that they were attracted by the illusory motion. Moreover, behavioral changes between the two periods were reported for one of the lionesses, highlighting a reduction in self-directed behaviors and an increase in attentive behaviors, and suggesting positive welfare implications. Thus, behavioral observations made before and during the presentation of the stimuli showed that our visual enrichment actually provided positive effects in lionesses. These results call for the development of future studies on the use of visual illusions in the enrichment programs of zoo animals.

Effects of a combined enrichment intervention on the behavioural and physiological welfare of captive Asiatic lions (Panthera leo persica)

“…In this study, we measured two traditional negative welfare parameters like ARB (Mason and Latham, 2004) and faecal corticosterone levels (Schildkraut, 2016;Vaz et al, 2017) along with two positive welfare indicators (Miller et al, 2020) viz., spread of participation index (SPI) (Cabana et al, 2018;Powell, 1995) and behaviour diversity (Pastorino et al, 2017). Previous studies on captive African lions that establish the positive effects of enrichment interventions have primarily relied on behavioural welfare indices (Martínez-Macipe et al, 2015;Ncube and Ndagurwa, 2010;Powell, 1995;Regaiolli et al, 2019;Van Metter et al, 2008). Our study is the first to showcase both the behavioural and physiological impacts of enrichment interventions in captive Asiatic lions housed in a conservation breeding programme.…”

“…While previous studies have tested the welfare impacts of food (Powell, 1995;Van Metter et al, 2008), manipulable (Powell, 1995), sensory (Martínez-Macipe et al, 2015;Regaiolli et al, 2019) and social stimulation (Leonard, 2008;Ncube and Ndagurwa, 2010) individually. This is the first control trial study to test the efficacy of a combined enrichment strategy on the welfare of Asiatic lions.…”

Does age affect perception of the Speech-to-Song Illusion?

“…If NST, a model of language processing, does provide an adequate account of the Speechto-Song Illusion, and there is an age-related difference in the perception of this auditory illusion, perhaps we need to look for that difference in infants before the language system has fully developed using the head-turn preference procedure commonly used to study language development in infants [41]. Recent research shows that some zoo animals experience certain PLOS ONE perceptual illusions [2], suggesting that the mechanisms responsible for certain perceptual illusions may have evolutionarily old origins. Given the later evolutionary emergence of language it might be useful to test whether other animals that do not use language also experience the Speech-to-Song Illusion.…”

“…Perceptual illusions occur when our percept does not match what is actually in the environment. Although illusions provide the general public (and zoo animals [2]) with entertainment, perceptual illusions also provide psychologists with a way to examine the limits of our perceptual and cognitive systems, thereby increasing our fundamental understanding of these systems [3,4].…”

Phonological but not semantic influences on the speech-to-song illusion

“…As “the dress” (https://en.wikipedia.org/wiki/The_dress) and the Yanny-Laurel debate (https://en.wikipedia.org/wiki/Yanny_or_Laurel) of recent internet fame suggest, visual and auditory illusions capture the interest of the general public. In addition to entertaining the general public and zoo animals (Regaiolli et al, 2019), perceptual illusions provide researchers with another way to examine the limits of the perceptual and cognitive systems involved in various illusions, thereby increasing our fundamental understanding of these systems (Gregory, 1968; see also Boyette et al, 2020; Vitevitch, 2003; Vitevitch & Donoso, 2011; Vitevitch & Siew, 2017).…”