Mirror Self-Recognition in Pigeons: Beyond the Pass-or-Fail Criterion

Roosters do not warn the bird in the mirror: The cognitive ecology of mirror self-recognition

Touching a mark on the own body when seeing this mark in a mirror is regarded as a correlate of self-awareness and seems confined to great apes and a few further species. However, this paradigm often produces false-negative results and possibly dichotomizes a gradual evolutionary transition of self-recognition. We hypothesized that this ability is more widespread if ecologically tested and developed such a procedure for a most unlikely candidate: chickens (Gallus gallus domesticus). Roosters warn conspecifics when seeing an aerial predator, but not when alone. Exploiting this natural behavior, we tested individual roosters alone, with another male, or with a mirror while a hawk's silhouette flew above them. Roosters mainly emitted alarm calls in the presence of another individual but not when alone or seeing themselves in the mirror. In contrast, our birds failed the classic mirror test. Thus, chickens possibly recognize their reflection as their own, strikingly showing how much cognition is ecologically embedded.

Supervised machine learning aided behavior classification in pigeons

Manual behavioral observations have been applied in both environment and laboratory experiments in order to analyze and quantify animal movement and behavior. Although these observations contributed tremendously to ecological and neuroscientific disciplines, there have been challenges and disadvantages following in their footsteps. They are not only time-consuming, labor-intensive, and error-prone but they can also be subjective, which induces further difficulties in reproducing the results. Therefore, there is an ongoing endeavor towards automated behavioral analysis, which has also paved the way for open-source software approaches. Even though these approaches theoretically can be applied to different animal groups, the current applications are mostly focused on mammals, especially rodents. However, extending those applications to other vertebrates, such as birds, is advisable not only for extending species-specific knowledge but also for contributing to the larger evolutionary picture and the role of behavior within. Here we present an open-source software package as a possible initiation of bird behavior classification. It can analyze pose-estimation data generated by established deep-learning-based pose-estimation tools such as DeepLabCut for building supervised machine learning predictive classifiers for pigeon behaviors, which can be broadened to support other bird species as well. We show that by training different machine learning and deep learning architectures using multivariate time series data as input, an F1 score of 0.874 can be achieved for a set of seven distinct behaviors. In addition, an algorithm for further tuning the bias of the predictions towards either precision or recall is introduced, which allows tailoring the classifier to specific needs.

Profiles of animal consciousness: A species-sensitive, two-tier account to quality and distribution

The science of animal consciousness investigates (i) which animal species are conscious (the distribution question) and (ii) how conscious experience differs in detail between species (the quality question). We propose a framework which clearly distinguishes both questions and tackles both of them. This two-tier account distinguishes consciousness along ten dimensions and suggests cognitive capacities which serve as distinct operationalizations for each dimension. The two-tier account achieves three valuable aims: First, it separates strong and weak indicators of the presence of consciousness. Second, these indicators include not only different specific contents but also differences in the way particular contents are processed (by processes of learning, reasoning or abstraction). Third, evidence of consciousness from each dimension can be combined to derive the distinctive multi-dimensional consciousness profile of various species. Thus, the two-tier account shows how the kind of conscious experience of different species can be systematically compared.

Through the looking glass: how do marked dolphins use mirrors and what does it mean?

Mirror-guided self-inspection is seen as a cognitive hallmark purportedly indicating the existence of self-recognition. Only a few species of great apes have been reported to pass a standard mark test for mirror self-recognition in which animals attempt to touch a mark. In addition, evidence for passing the mark test was also reported for Asian elephants, two species of corvids, and a species of cleaner fish. Mirror self-recognition has also been claimed for bottlenose dolphins, using exposure of marked areas to a mirror as evidence. However, what counts as self-directed behaviour to see the mark and what does not has been debated. To avoid this problem, we marked the areas around both eyes of the animals at the same time, one with visible and the other with transparent dye to control for haptic cues. This allowed the animal to see the mark easily and us to investigate what side was exposed to the mirror as an indicator for mark observation. We found that the animals actively chose to inspect their visibly marked side while they did not show an increased interest in a marked conspecific in the pool. These results demonstrate that dolphins use the mirror to inspect their marks and, therefore, likely recognise a distinction between self and others.

A preliminary attempt to investigate mirror self-recognition in Octopus vulgaris

Mirror self-recognition (MSR) is a potential indicator of self-awareness. This capability has been widely investigated among vertebrates, yet it remains largely unstudied in invertebrates. Here we report preliminary data about behavioural responses exhibited by common octopuses (Octopus vulgaris) toward reflected images of themselves and explore a procedure for marking octopus’ skin in order to conduct the Mark test. Octopuses (n = 8) received four familiarization trials with a mirror and four familiarization trials with a control stimulus: a non-reflective panel (Panel group, n = 4) or the sight of a conspecific housed in an adjacent tank (Social group, n = 4). Subsequently, octopuses were marked with non-toxic nail polish in the area where the Frontal White Spots are usually expressed, and they received one test trial with the mirror and one control trial with no mirror. We found that octopuses in the Panel group tended to exhibit a stronger exploratory response toward the mirror than the non-reflective panel, but performed agonistic responses only in the presence of the mirror. In contrast, octopuses in the Social group exhibited comparable exploratory and agonistic behaviours toward the mirror and the sight of the conspecific. In the Mark test, octopuses frequently explored the mark via their arms. However, mark-directed behaviours were also observed in the absence of the mirror and in sham-marked individuals, thus suggesting that proprioceptive stimuli drove these responses. Despite the limitations associated with our marking procedure, the baseline data collected in this pilot study may facilitate the further testing of MSR in the octopus and other cephalopods.