N ico O rlandi The richness of environmental stimuli and the embodiment and time extension of perception help Gibson understand how perceiving subjects deal with sensory data without invoking internal inferential and representational structures Such structures are needed, according to Gibson, only if we conceive of perception as a static process, where the visual system needs to continuously store and add information to an impoverished stimulus By contrast, Gibson thinks that the perceptual act is an active engagement with the world Proponents of this kind of position tend to liken perceiving to the type of engagement present in the tactual modality (Noë 2004) Learning the shape of something by touch requires continuously exploring the object as opposed to trying to form a model of the shape based on a single encounter Accordingly, perceiving requires the direct ‘pick-up’ of information in a rich biological context in which perceivers can move and explore Gibson admitted that the brain needs to somehow attune, and respond to the environment it encounters But he tried to explain this attunement by using a resonance metaphor The information in the stimulus simply causes the appropriate neural structures in the brain to fire and resonate (Gibson 1966; 1979) The metaphor of resonance – which was perhaps influenced by the work of Köhler – remained underdescribed in Gibson, and it was later at the center of criticism David Marr, for example, while accepting many Gibsonian insights, remarked that ignoring the details of how the brain attunes to the world amounts to oversimplifying the perceptual task (Marr 1982) Marr and other constructivists can be read as trying to supplement what Gibson left unexplained: the internal computational basis of perception More recent developments in computer science, such as connectionism, may supplement what Gibson and Köhler had in mind without committing to constructivism (Churchland 1990; Feldman 1981; Grossberg 1982; McClelland and Rumelhart 1986; Rosenblatt 1962) Connectionist networks are nets of connected units that spread information, and attune to the world, by spreading levels of activation – simulating a biological brain It is open to debate whether such networks make use of representations and perform inferential operations (Ramsey et al 1991) Gibson’s work inspired a number of philosophers and psychologists in the second half of the 20th century and his influence continues today His ideas have been borrowed in various ways in the literature on so-called ‘embodied and embedded cognition’ in philosophy and in psychology This literature puts into question the need to appeal to representations in the study of mental processes (Clark 1997; Geisler 2008; Hurley 2002; O’Regan and Noë 2001; Orlandi 2014; Wilson 2004) Although contemporary philosophers of perception often refer back to Gibson, it should be noted that the stress on understanding perceptual processes as embodied and ecologically situated is present in the continental tradition in the first half of the twentieth century – in particular, in Maurice Merleau-Ponty (Merleau-Ponty 1945) According to Merleau-Ponty, there is a type of ‘readiness’ on the part of the subject in perception that makes an object 118