Experimenter expectancy bias does not explain Eurasian jays’ (Garrulus glandarius) performance in a desire-state attribution task.

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. this behavior is that the male encoded the female's decreased desire for the food she was sated on, and adjusted his behavior accordingly. However, in these studies, the male's actions were scored by experimenters who knew on which food the female was sated. Thus, it is possible that the experimenters' expectations (sub-consciously)affected their behavior during tests that, in turn, inadvertently could have influenced the males' actions. Here, we repeated the original test with an experimenter who was blind to the food on which the female was sated. This procedure yielded the same results as the original studies: the male shared food with the female that was in line with her current desire. Thus, our results rule out the possibility that the Eurasian jay males' actions in the food sharing task could be explained by the effects of an experimenter expectancy bias.3

Carrion crows (Corvus corone corone) fail the mirror mark test yet again.

“…Corvids are known for their cognitive sophistication (Brecht, Hage, Gavrilov, & Nieder, 2019; Clayton & Emery, 2015; Ditz & Nieder, 2016; Moll & Nieder, 2015; Nieder, 2017), and their social–cognitive abilities specifically. For example, Eurasian jays have been reported to flexibly respond to the desires of their partner (Ostojić et al, 2016; Ostojić, Shaw, Cheke, & Clayton, 2013), and ravens and California scrub-jays seem to be sensitive to the perspective and knowledge of their conspecifics (Bugnyar, Reber, & Buckner, 2016; Dally, Emery, & Clayton, 2006). This behavior has earned corvids the title of “feathered apes” (Emery, 2004)—but do they share the capacity for self-recognition with some of the great apes, too?…”

Little evidence that Eurasian jays protect their caches by responding to cues about a conspecific’s desire and visual perspective

“…For instance, the fact that we could not find support that Eurasian jays respond to cues about others’ current mental states in the caching context does not necessarily challenge the reliability of the evidence about similar behaviours in other contexts. For example, in the cooperative context of food sharing, the effect whereby males adjust the pattern of food shared with the female to her specific satiety ( Ostojić et al, 2013 ) has been reliably shown by the same males in subsequent studies ( Legg, 2015 ; Ostojić et al, 2014 ; Ostojić et al, 2016 ). One difference between the cache-protection and the food-sharing context may be the motivation of the jays to reliably exhibit the behaviour in question.…”

“…Corvids are a group of large-brained birds that are hypothesised to have evolved sophisticated cognitive abilities independently from primates ( Clayton and Emery, 2015 ; Emery and Clayton, 2004 ; Güntürkün and Bugnyar, 2016 ; Osvath et al, 2014 ; Seed et al, 2009 ). This group represents a good model for this line of research because they might be capable of responding – independently – to social cues correlating with different types of mental states (perspective: Bugnyar et al, 2016 ; Dally et al, 2004 ; Dally et al, 2005 ; Legg et al, 2016 ; Legg and Clayton, 2014 ; Shaw and Clayton, 2013 ; Stulp et al, 2009 ; desires: Ostojić et al, 2013 , Ostojić et al, 2016 , Ostojić et al, 2017 Apperly and Butterfill, 2009 ; knowledge: Bugnyar and Heinrich, 2005 ; Dally et al, 2006 ; Emery and Clayton, 2001 ). In particular, previous research has reported that Eurasian jays ( Garrulus glandarius ) may be able to adjust their behaviour according to cues that correlate with the perspective and current desire of a conspecific.…”

“…In the presence of a conspecific competitor, these jays have been reported to preferentially cache food in less visible locations (e.g., behind barriers, at distance), or in non-noisy substrates, which has been interpreted as a potential response to the visual ( Legg et al, 2016 ; Legg and Clayton, 2014 ) or acoustic perspective ( Shaw and Clayton, 2013 ) of a potential pilferer. In parallel, research investigating food-sharing behaviour found that male Eurasian jays change the type of food shared with their female partner, depending on which food the female has been sated on, and therefore which she desires ( Ostojić et al, 2013 ; Ostojić et al, 2014 ; Ostojić et al, 2016 ). In a recent study, a similar response to another’s satiety has also been reported in the context of caching, whereby Eurasian jays and Western scrub-jays preferentially cached food that an observer, and thus potential pilferer, was sated on Ostojić et al, 2017 .…”

Little evidence that Eurasian jays (Garrulus glandarius) protect their caches by responding to cues about a conspecific’s desire and visual perspective

“…Corvids are a group of large-brained birds that are hypothesised to have evolved sophisticated cognitive abilities independently from primates (Clayton and Emery, 2015; Emery and Clayton, 2004; Güntürkün and Bugnyar, 2016; Osvath et al, 2014; Seed et al, 2009). This group represents a good model for this line of research because they might be capable of responding – independently – to social cues correlating with different types of mental states (perspective: Bugnyar et al, 2016; Dally et al, 2004, 2005; Legg et al, 2016; Legg and Clayton, 2014; Shaw and Clayton, 2013; Stulp et al, 2009; desires: Ostojić et al, 2013, 2016, 2017; knowledge: Bugnyar and Heinrich, 2005; Emery and Clayton, 2001). In particular, previous research has reported that Eurasian jays ( Garrulus glandarius ) may be able to adjust their behaviour according to cues that correlate with the perspective and current desire of a conspecific.…”