The Eurasian magpie is the only non-mammal species known to be able to recognize itself in a mirror test. Magpies have been observed taking part in elaborate grieving rituals, which have been likened to human funerals, including laying grass wreaths. Marc Bekoff, at the University of Colorado, argues that it shows that they are capable of feeling complex emotions, including grief. Furthermore, carrion crows show a neuronal response that correlates with their perception of a stimulus, which some scientists have argued to be an empirical marker of (avian/corvid) sensory consciousness – the conscious perception of sensory input – in the crows which do not have a cerebral cortex. A related study shows that the birds' pallium's neuroarchitecture is reminiscent of the mammalian cortex.