Interface Theory vs Gibson: An Ontological Defence of the Ecological Approach Andrew D Wilson Corresponding author details: School of Social Sciences, Leeds Beckett University, Leeds UK Email: [email protected] / [email protected] Web: https://cognitioninaction.wordpress.com/ Twitter: @PsychScientists 1 Acknowledgments I would like to thank Agnes Henson and Sabrina Golonka for their advice and comments on this paper. 2 Abstract Interface theory (Hoffman, Singh & Prakesh, 2015) is the radical hypothesis that fitness, not truth, dictates the evolution of perceptual systems. They show, with simulations, that this means veridical mappings (ones that preserve at least some of the structure of the world) are routinely out- competed by non-veridical interfaces. They take particular aim at the direct perception, ecological approach to perception (Gibson, 1966, 1979; Turvey, Shaw Reed & Mace, 1981) and work to show that such a system never gets out of the evolutionary gate. This commentary defends the ecological approach from the supposedly radical implications of interface theory by showing that a) Gibson does not make the mistakes he is accused of and, more substantively b) that the ecological hypothesis is so different in kind to the inferential, representational view of perception that it simply falls outside the scope of interface theory’s critiques. The heart of this defence is identifying the profoundly different ontologies (assumptions about the nature of the world to be perceived) underlying inferential and ecological approaches. The ecological ontology makes the direct perception of behaviourally relevant properties of the world possible, no inference required, and I will review how modern ecological psychology scientifically investigates this hypothesis. Interface theory is a strong, clear formalisation of the inferential world-view, but it has no implications for the ecological approach and the scientific game remains afoot. 3 Introduction Hoffman, Singh & Prakesh (2015; hence HS&P) propose a supposedly radical take on the nature of perceptual experience in the form of their interface theory. They begin with the mainstream assumption that perception is an inferential, representational process. These mental representations implement a mapping function to convert the physical world into the perceived world; HS&P call these interfaces. In a series of evolutionary simulations, HS&P compete all possible types of mapping functions against one another and demonstrate the surprising result that veridical interfaces (mappings that preserve at least some of the structure of the environment) are routinely out- competed into extinction by non-veridical interfaces (mappings built in whatever form required to optimise fitness). Perception, they argue, is a non-veridical but adaptive interface that hides the messy details of the “true” world and instead presents us with a series of behaviourally useful fictions, including things such as ‘objects’ and ‘events’. One theory of perception that seems to immediately lose in this scenario is James J Gibson’s direct perception, ecological approach (Gibson, 1966, 1979; Michaels & Carello, 1981; Turvey, Shaw, Reed & Mace, 1981). Gibson rejected the notion of internal mental representations performing information processing; instead, he proposed a theory of ecological information which is sufficient to support adaptive behaviour without further mental processing. If perception does not involve transforming the raw sensory data into anything else, then what we see is what the world is and perception should be veridical. If, however, HS&P are right and evolution will always favour non- veridical perceptual systems over veridical ones, then evolution will never produce a Gibsonian organism and the ecological approach is dead on arrival. HS&P of course argue precisely this. This commentary defends Gibson and the ecological approach from the specific objections HS&P raise. The paper will work as follows. HS&P have three specific problems with the ecological approach. Two of the objections (about information processing and illusions) are not specific to interface theory and I can deal with them quickly with reference to the relevant literature. I will then 4 detail the primary objection, that Gibson’s ecological approach is a form of veridical perceptual mapping strategy that falls victim to the various results from interface theory. The primary line of defence is philosophical, and it is the claim that the ecological and inferential approaches to perception are so ontologically different in kind that the challenge posed by HS&P comes nowhere near Gibson. I will detail the two ontologies and their implications, then detail how the modern ecological approach has formalised its ontology into a science of affordances and perceptual information. This analysis will show two things. First, interface theory is not so radical; it is actually a fairly standard inferential, representational theory of perception, and the various radical results actually just reflect the long-standing and unsolved problem of symbol grounding. Second, it will make it clear that the radically different understanding of perception is actually the ecological approach, and that this difference runs deep enough that the results of interface theory have nothing to say about Gibson’s theory. Interface theory is not our problem. Some Objections to the Ecological Approach HS&P (2015) propose these specific errors in Gibson’s approach; First, Gibson got evolution wrong: He claimed that evolution shapes veridical perceptions of those aspects of the world that have adaptive significance for us. Thus Gibson proposed naïve realism, not the interface theory ... Second, Gibson denied that perception involves information processing. The interface theory does not. Evidence for information processing is now overwhelming. ... Third, in place of information processing Gibson proposed direct perception...[but] How could a theory of direct perception explain illusions? Gibson never solved this problem (Fodor & Pylyshyn, 1981)… 5 pg 1500 The first objection actually comes in two parts; the evolutionary supremacy of non-veridical interfaces and the Invention of Symmetry theorem. I will tackle these interface theory specific objections last. Objections 2 & 3 are nothing new and can be easily addressed with reference to the existing literature, so I will address those quickly first. The Status of Information Processing There is indeed a great deal of evidence in favour of the information processing approach. There is also, however, extensive empirical support for the hypothesis that ecological information shapes behaviour directly (e.g. coordinated rhythmic movement, e.g. Wilson & Bingham, 2008; Wilson, Collins & Bingham, 2005a, b; the outfielder problem, e.g. Fink, Foo & Warren, 2009; McBeath, Shaffer & Kaiser, 1995). This work typically shows that the observed structure in behaviour is explained by the observed structure in the information, suggesting no mediation or transformation has occurred in between perception and action. Neuroscientists have also finally begun investigating the neural dynamics associated with detecting and using ecological information and have shown the nervous system preserves, rather than transforms, the spatio-temporal dynamics of the information which then directly structures behaviour (e.g. van der Meer, Svantesson & van der Weel, 2012). In addition, on the few occasions ecological and information processing approaches have been explicitly pitted against one another, the ecological approach prevails (e.g. informational strategies beat trajectory prediction in the outfielder problem, Fink, Foo & Warren, 2009; information beats cue integration in distance perception, Mon-Williams & Bingham, 2008; smart perceptual mechanisms beat schema learning in skill acquisition, Zhu & Bingham, 2010; nulling informational errors beats internal simulations of vehicle dynamics; Markkula, Benderius & Wahde, 2014). Rumours that the ecological approach has been overwhelmed have therefore been greatly exaggerated. 6 Illusions Fodor & Pylyshyn (1981) do indeed claim Gibson cannot explain illusions, but Gibson of course had plenty to say about illusions; he just did not consider them to be of central interest to a theory of perception. de Wit, van der Camp & Withagen (2015) provide a useful review of Gibson’s published discussions on illusions in both his 1966 and 1979 books, as well as his extensive related analyses of the information available in pictures of things (e.g. Gibson, 1971; Gombrich, Arnheim & Gibson, 1971). That Fodor & Pylyshyn paper also sparked a substantial defence of Gibson by Turvey, Shaw, Reed and Mace (1981) which included an extensive analysis of the ecological approach to misperception and illusion (Section 8, ‘Misperception Misconstrued’). Since then, ecological psychologists have continued to engage empirically with illusion phenomena. For example, Runeson (1988) developed an informational analysis of the Ames Room, while Zhu & Bingham (2011) and Zhu, Shockley, Riley & Bingham (2013) argue, with data, that the size-weight illusion is not a misperception of weight but the correct perception of throwability. Paying attention to the informational basis of perception also helps explain when illusions such as the McGurk effect obtain and when they don’t (e.g. Brancazio, Best & Fowler, 2006; Rosenblum & Saldaña, 1996). Claiming the ecological approach has nothing to say about illusions is therefore just demonstrably