With a very interesting theory based on several psychological dimensions (functionalist, mentalistic, and culture-based dimensions), Michelle Ann Kline proposes a functionalist approach for teaching behavior in human and nonhuman animals. Her goal is to integrate teaching mechanisms for humans and other animals into a unified theoretical framework. The author suggests several macroscopic mechanisms like “evaluative feedback,” “social tolerance,” or “stimulus enhancement” in order to understand teaching behaviors in animal species. However, in our view, to better understand a behavior such as “teaching,” we need to first explore and to grasp the lowest common denominator among species. According to Wilson (Reference Wilson2002), “Science is not ultimately about explaining the causality of any particular event. Instead, it is about understanding fundamental principles of organization and function” (p. 630). Consequently, without denying the importance of several macroscopic mechanisms, we stress in our commentary that it is much more important to fully understand the fundamental principle for teaching behaviors among species.

For Schütz-Bosbach and Prinz (Reference Schütz-Bosbach and Prinz2007), successful social interaction comes from a simple mechanism called “perceptual resonance.” In this theory, and adapted for teaching skills, the learner is able to pick up and store perceptual consequences on the environment from the observation of the teacher's actions. This perceptual mechanism for perceived events might represent the basis for efficient social interaction, and teaching behaviors. For example, the perception of a relevant action can create an abstract semantic of Arabic numbers for observers (Badets & Pesenti Reference Badets and Pesenti2010). In this study, participants had to verbally enumerate a small or large (2 or 8) number after the processing of finger movements such as a finger-grip closing. Results revealed that the perception of a finger closing movement slowed down the enumeration of large numbers. This interference comes from the different magnitudes of finger movements and numbers. Specifically, the small magnitude required for finger-grip closing toward a small object is incompatible with the large magnitude processed from a large Arabic number. In this view, the perception of a relevant action toward the environment can afford a more abstract semantic. Therefore, Badets and Pesenti (Reference Badets and Pesenti2010) suggest that: “Communication, language and conceptual knowledge related to concrete objects may rely on the sensory–motor systems from which they emerge” (p. 46).

Adapted for the theory of perceptual resonance, the perception of relevant features in the environment from a teacher's action can afford more efficiently related abstract semantics, which represent core information in human culture. To support this hypothesis, we recently revealed that the observation of a finger-grip closing enhanced the enumeration of small numbers during a random number generation task (Badets et al. Reference Badets, Bouquet, Ric and Pesenti2012). For a cultural invention like arithmetic, we revealed the same perceptual mechanism (Badets et al. Reference Badets, Pesenti and Olivier2010). In this study, participants resolved simple addition more efficiently after the simulation of finger configuration from another person showing the correct answer. For Badets and colleagues, “During arithmetic learning, these outcomes (i.e., the finger–numeral configurations) overlap with the responses and are mentally activated when having to retrieve the responses of the arithmetic operations” (Badets et al. Reference Badets, Pesenti and Olivier2010, p. 21). There is a perceptual resonance between teacher and learner through the processing of relevant outcomes. In the same vein, Pickering and Garrod (Reference Pickering and Garrod2013) have recently posited a comparable perceptual mechanism for language production and comprehension. In this theory, production and comprehension are not distinct, but are intertwined throughout perceptual and simulation mechanism. Consequently, we claim that teaching does not come from dyadic behaviors between a teacher and a learner but from a fundamental triadic principle implying action for others, perception from others, and the storage of relevant events in the environment.

Studies on tool use are also consistent with the perceptual resonance hypothesis. For instance, recent neuropsychological evidence indicates that brain-damaged patients with apraxia fortool use are impaired in forming an accurate representation of the perceptual consequences of the actions performed by tools (for reviews, see Goldenberg Reference Goldenberg2013; Osiurak Reference Osiurak2014; Osiurak et al. Reference Osiurak, Jarry and Le Gall2010; Reference Osiurak, Jarry and Le Gall2011). These difficulties are strongly associated with lesions of the left inferior parietal lobe, a region which is specifically activated when people observe tool use actions made by others (e.g., van Elk Reference van Elk2014). Evidence also comes from experimental studies, wherein participants have to observe another person performing a tool action (e.g., touching a target by making a lever action) before carrying out the action themselves (see Massen & Prinz Reference Massen and Prinz2009). The findings stress that participants are faster and commit fewer errors when the action made by the model is congruent with the action they have to perform, independently of the congruency of the motor actions. These findings confirm that people benefit from the observed perceptual consequences of the action made by others. Interestingly, the idea that animal users such as nonhuman primates can also learn from conspecifics based on the observed perceptual consequences of tool actions, has also received great support (e.g., Horner & Whiten Reference Horner and Whiten2005).

Finally, for Kline's ultimate question, “Why humans teach more than other animals” (target article, sect. 7), we would like to suggest that only humans are able to efficiently reuse an old inherited perceptual mechanism for several new cultural inventions, such as numbers or tools. As suggested by Anderson (Reference Anderson2010), a fundamental principle of the brain is to exploit well-established neuronal circuitry for various different functions. The perceptual resonance mechanism is an action-perception mechanism that might have been present in humans and nonhuman animals for millions of years (Cisek & Kalaska Reference Cisek and Kalaska2001; Shin et al. Reference Shin, Proctor and Capaldi2010). The human brain might have been able to reuse its property for new cultural inventions like spoken language (Pickering & Garrod Reference Pickering and Garrod2013), calculation (Badets & Pesenti Reference Badets and Pesenti2010), or tool use (Osiurak & Badets Reference Osiurak and Badets2014). However, why only humans have been able to exploit this mechanism for other purposes such as cultural objects and teaching is an open question, and probably the most important for researchers.