Local Dot Motion, Not Global Configuration, Determines Dogs’ Preference for Point-Light Displays

Abstract

Simple SummaryAnimal motion is characterised by predictable kinematics according to their body morphology and the laws of gravity. This pattern of movement, called biological motion, is traditionally studied using animated displays created by placing a small number of light dots on the major joints of living beings. Previous studies have shown that several animal species can reliably discriminate dot displays depicting an animal walking, and their performance is impeded when the display is turned upside-down and is variably affected when each dot is displaced to disrupt the global biological arrangement. In this study, we investigated this phenomenon in dogs during the presentation of dot displays depicting humans or dogs walking. Our findings showed that dogs preferred to view the display which depicted an upright dog, regardless of its global arrangement, and had no significant preferences when displays depicting humans were presented. This suggests that dogs’ sensitivity to biological motion depends mainly on the presence of dot motion that moves in accordance with gravity. Also, our findings suggest that, despite dogs’ extensive exposure to human motion, they are not sensitive to the bipedal motion presented in the human dot displays.AbstractVisual perception remains an understudied area of dog cognition, particularly the perception of biological motion where the small amount of previous research has created an unclear impression regarding dogs’ visual preference towards different types of point-light displays. To date, no thorough investigation has been conducted regarding which aspects of the motion contained in point-light displays attract dogs. To test this, pet dogs (N = 48) were presented with pairs of point-light displays with systematic manipulation of motion features (i.e., upright or inverted orientation, coherent or scrambled configuration, human or dog species). Results revealed a significant effect of inversion, with dogs directing significantly longer looking time towards upright than inverted dog point-light displays; no effect was found for scrambling or the scrambling-inversion interaction. No looking time bias was found when dogs were presented with human point-light displays, regardless of their orientation or configuration. The results of the current study imply that dogs’ visual preference is driven by the motion of individual dots in accordance with gravity, rather than the point-light display’s global arrangement, regardless their long exposure to human motion.

Do dogs mind the dots? Investigating domestic dogs' (Canis familiaris) preferential looking at human‐shaped point‐light figures

“…Other non‐human animals tested with conspecific‐shaped PLFs using discrimination tasks, including visual search tasks, include pigeons (Dittrich, Lea, Barrett, & Gurr, 1998; Qadri, Asen, & Cook, 2014; Troje & Aust, 2013; Watanabe & Troje, 2006; Yamamoto, Goto, & Watanabe, 2015), chimpanzees (Tomonaga, 2001), baboons (Parron, Deruelle, & Fagot, 2007) and rats (MacKinnon, Troje, & Dringenberg, 2010). Second, research has also used methods that study animals' spontaneous preference for certain types of PLFs, testing approaching behaviour in chicks (Regolin, Tommasi, & Vallortigara, 2000; Vallortigara, Regolin, & Marconato, 2005; Yamaguchi & Fujita, 1999) and quails (Yamaguchi & Fujita, 1999) and preferential looking in marmosets (Brown, Kaplan, Rogers, & Vallortigara, 2010) and in dogs (Eatherington, Marinelli, Lõoke, Battaglini, & Mongillo, 2019; Ishikawa, Mills, Willmott, Mullineaux, & Guo, 2018; Kovács et al, 2016).…”

“…However, no such effect of scrambling but an effect of inversion was found on approaching preference in chicks (Vallortigara & Regolin, 2006). Second, some of the above studies concluded that animals were capable of detecting biological motion in PLFs (Brown et al, 2010; Dittrich et al, 1998; Ishikawa et al, 2018; Kovács et al, 2016; Regolin et al, 2000; Troje & Aust, 2013; Vallortigara et al, 2005; Watanabe & Troje, 2006; Yamaguchi & Fujita, 1999), whereas others reported negative results and stated that the positive findings of animals recognising biological motion in PLFs may be due to animals using certain configurational properties of the PLF, that is paying attention to sub‐configurations of the dots rather than perceiving the PLF stimulus as a whole representing conspecifics (Eatherington et al, 2019; Parron et al, 2007; Qadri et al, 2014; Tomonaga, 2001; Yamamoto et al, 2015). In particular, when animals gain food or are reinforced during repeated training occasions, they have the chance to learn about configurational properties of PLFs.…”

“…Therefore, learning effects should be considered when using PLFs in animal studies. Indeed, it seems that in experiments that rely on spontaneous behaviour rather than on learning tasks (Eatherington et al, 2019; Ishikawa et al, 2018; Kovács et al, 2016; Regolin et al, 2000; Vallortigara & Regolin, 2006; Vallortigara et al, 2005; Yamaguchi & Fujita, 1999), a preferential looking at PLFs showing biological motion was present. Similar design was also applied in human infants, where a preferential looking paradigm with simultaneous presentation of PLFs has shown that infants prefer to look at PLFs representing biological motion compared to PLFs that do not show biological motion (Di Giorgio et al, 2016; Simion, Regolin, & Bulf, 2008).…”

“…Thus, the question remains open whether non‐human animals recognise the global shape and form of PLFs, suggesting that they may consider PLFs as representing conspecifics depicting biological motion (Ishikawa et al, 2018; Kovács et al, 2016), or whether they memorise and rely on the configurational properties (i.e. sub‐configurations of the dots; Eatherington et al, 2019; Parron et al, 2007; Tomonaga, 2001) to detect biological motion. Recently, it has been reported that dogs looked longer (Kovács et al, 2016) or preferred to look at (Ishikawa et al, 2018) human‐shaped PLFs depicting biological motion compared to PLFs with a random motion pattern.…”

“…Recently, it has been reported that dogs looked longer (Kovács et al, 2016) or preferred to look at (Ishikawa et al, 2018) human‐shaped PLFs depicting biological motion compared to PLFs with a random motion pattern. Yet, to date, only one study has focused on the influence of scrambling and/or inverting PLFs upon dogs' preferential looking at human‐shaped PLFs compared to simultaneously presented non‐human‐shaped PLFs (Eatherington et al, 2019). This study did not find preferential looking at human‐shaped PLFs, which were laterally oriented, compared to their scrambled and/or inverted counterparts.…”