Extended Cognition; Parity Principle; Mutual Manipulability; Matched Interlevel Experiments; spider cognition

If cognition extends beyond the boundaries of the body, what in the environment can be considered cognitive? To answer this question, one needs a criterion that separates cognitive components from supplementary, non-cognitive entities, and some criteria, such as the Parity Principle or the Mutual Manipulability, have indeed been proposed. However, recent research has pointed out that such criteria have problems in demarcating components, either admitting too many objects as cognitive (cognitive bloat), or admitting supposedly illogical causal relationships between the parts and the whole. Here we apply an updated version of Mutual Manipulability criterion, the “Matched Interlevel Experiments” (MIE). We analyzed published experiments performed on orb-web spiders through the MIE. We investigated the applicability of the new criterion and, based on that, we assessed the presence of Extended Cognition. These investigations took place through the application of the MIE on two groups of experiments. The first group results in the acceptance the web as a constituent of the spider's perceptual system, while the second group results in the acceptance of the web as a constituent of the spider’s decision making process. Through these applications, it was possible to analyze the potential and limitations of the MIE. Although we conclude that the web constitutes both the spider's perceptual and decision- making process, we also point that if the classical separation between perception and cognition is to be adopted, the web would be conceived merely as a supplementary entity, or a media for perception. Also, if communicative media (e.g. air, luminosity) are to be considered as components of cognition, then an excess of entities would have to be admitted, leading to the problem of cognitive bloat. Finally, by advocating for the abandonment of the classical separation between perception and cognition, we conclude with the acceptance of cognitive processes beyond the brain, which include the body and the environment close to the body (such as the orb-web).