Do New Caledonian crows solve physical problems through causal reasoning?

Abstract

The extent to which animals other than humans can reason about physical problems is contentious. The benchmark test for this ability has been the trap-tube task. We presented New Caledonian crows with a series of two-trap versions of this problem. Three out of six crows solved the initial trap-tube. These crows continued to avoid the trap when the arbitrary features that had previously been associated with successful performances were removed. However, they did not avoid the trap when a hole and a functional trap were in the tube. In contrast to a recent primate study, the three crows then solved a causally equivalent but visually distinct problem-the trap-table task. The performance of the three crows across the four transfers made explanations based on chance, associative learning, visual and tactile generalization, and previous dispositions unlikely. Our findings suggest that New Caledonian crows can solve complex physical problems by reasoning both causally and analogically about causal relations. Causal and analogical reasoning may form the basis of the New Caledonian crow's exceptional tool skills.

Of babies and birds: complex tool behaviours are not sufficient for the evolution of the ability to create a novel causal intervention

“…New Caledonian crows have demonstrated an abstract understanding of object-object interactions [25,27] and the ability to reason about hidden causal agents [26,28,29]. Interestingly, both this species [18,30] and Eurasian jays (Garrulus glandarius) [31] actually outperform children up to the age of seven [32] on certain object discrimination tests of physical cognition using the Aesop's fable paradigm, such as choosing between sinking and floating (or hollow and solid) objects.…”

Individual variation in cognitive performance: developmental and evolutionary perspectives

“…Thus, an unfortunate learned association could potentially mask some subjects' true abilities. Similarly, in trap-tube tests on New Caledonian crows (Corvus moneduloides), Taylor et al [14] argued that failures by some subjects may have resulted from difficulties in inhibiting the tendency to pull food towards themselves. Standardized measures of inhibitory control, coupled with detailed analyses of behaviour during successes and failures, as advocated by Seed et al [13] and Chappell & Hawes [16] may also prove highly informative in determining the causes of variation in performance.…”

“…It is therefore difficult to say with certainty that individuals that pass tests really possess the cognitive ability under investigation. Rather than giving subjects multiple trials of one or two transfer tests, a more powerful approach may be to provide them with a single trial of many different tests (see also [14]). Here, spontaneous correct performance despite variations in the visible characteristics of the apparatus would provide stronger evidence for an understanding of cause-and-effect.…”

Innovativeness as an emergent property: a new alignment of comparative and experimental research on animal innovation

“…The comparative approach was later extended to an analysis of behavioural innovations in primates, drawing upon both wild and captive observations [14][15][16]. The second methodology employs an individual or, more rarely, a species-level proxy of innovativeness, namely performance on novel problems, from manipulating objects to negotiating mazes to gain access to food or other desirable objects, such as offspring and nest decorations [17][18][19][20][21][22][23][24][25][26][27]. This measure of innovativeness is often referred to as innovative problem-solving.…”