I discuss Stoffregen & Bardy's theory from the perspective of the complementary aspect of input conflict, namely, imput coherence - the unity of perception. In a classical approach this leads to the famous “binding problem.” The conceptual framework the authors construct leaves no space for a binding problem to arise. A remaining problem of perceptual conflict, arising in cases of inversion of the visual field can be handled by the theory the authors propose.

The authors attempt to prove that single energy arrays cannot specify reality. We offer contrary evidence that motion structures the acoustic array to specify fundamental attributes of the source. Against direct detection in general, we cite evidence that humans weight acoustic inputs differentially when making perceptual judgments of auditory motion.

The propositions that the senses are separate and that the global array may be sufficient for adequate perception are questioned. There is evidence that certain tasks may be primarily “input-driven,” but these are a special case along the behavioral continuum. Many tasks involve sensory information that is ambiguous, and other sources of information may be required for adequate perception.

Overwhelming evidence points to the existence of separate sensory channels in the nervous system. The power of this type of parallel organization is that information is first processed in neurons specialized to code it most efficiently. However, sensory pathways are convergent and divergent at each level as well, as is necessary to interpret multimodal and conflicting information.

How to conceive the place of the brain in the specification of the animal environment relation? Reality is a continuum between external physical energies and brain energy. The global array concept linked to the physical world and its physical energies could be transposed to the brain as a physical object and a dynamical system.

The epistemological premises and scientific viability of Stoffregen & Bardy's ecological perspective are evaluated by analyzing the concept of direct perception of global invariants vis-à-vis (1) behavioral evidence that perception is based on the integration of modal sources of information and (2) neurophysiological aspects of the integration of sensory signals.

There is good neuropsychological evidence for an amodal, relational basis for perception and action. Using this idea, it may be possible to define more accurately what is meant by specificity, in the Gibsonian sense of the term. However, for complex organisms, and most especially for creative, open-ended perceivers and actors such as human beings, specification may not be relevant.

Stoffregen & Bardy provide grounds to suppose that specification requires global arrays and that this information is used by perceptual systems. Three conclusions follow from this supposition; (1) global specification will be taken seriously only if additional examples are discovered; (2) research into single-sense information must take global information into account, and (3) ecological psychologists must account for perceptions based upon non-specific information.

In perception science, an alternative to focusing on individual sensory systems is to describe the environment to be perceived. We focus on the emergent dynamics of human-environment interactions as an important category of the environment to be perceived. We argue that information about such dynamics is available in subtle patterns of movement variability that, of necessity, stimulate multiple sensory systems.

Stoffregen & Bardy's primary motivation for rejecting current views on specification in favor of the global array is that current forms of specification in single-energy arrays allow the ambiguous or inadequate specification of reality. I show that this motivation is not justified, and that the global array concept still falls prey to inadequate specification.

The global array might prove to be an important and even necessary concept for explaining some multi-modal phenomena from the specificational perspective. However, we suspect that specification exists in energy arrays detectable by single or multiple sensory systems. We argue for a more general modality-neutral perspective and review results from recent research on audiovisual speech perception.

Stoffregen & Bardy's proposal that perceptual systems can use information defined across two or more sensory domains is valuable and urgent in its own right. However, their claim of exclusive validity for global-array information is superfluous and perpetuated for incorrect reasons. The seeming ambiguities of individual arrays emanate from failures to consider relevant ecological constraints and higher-order variables.

The target article's value lies not in its defence of specification, or the “global array” concept, but in its challenge to the paradigm of 5+ senses, and its examples of multiple receptor types cooperatively participating in specific pick-up tasks. Rather than analysing our perceptual endowment into 5+ senses, it is more revealing to type perceptual systems according to task.

We show that Stoffregen & Bardy's arguments against the assumption of separately functioning senses have more historical antecedents than they give credit for, and that multimodal functioning – primitive in perceptual and brain development – does not require this assumption. What is needed is evidence that biological organisms are indeed detecting and acting upon information in a multimodal (or global) array.

In advocating an extreme form of specification requiring the abolition of separate senses, Stoffregen & Bardy run the risk of diverting attention from the multisensory integration of perception and action they wish to champion.

Infants are global perceivers. They detect patterns in stimulation that allow detection of many affordances of the environment. Pick-up of structural patterns across forms of ambient energy awaits maturation of sensory systems and improvements in motor skill, but development proceeds rapidly during the first year. Researchers in perceptual development must devise and refine existing tools to examine infants' abilities.

Various annoyingly incorrect statements of Stoffregen & Bardy are corrected, for example, that perception researchers commonly use the term “absolute motion” to denote motion without any frame of reference, confuse earth-relative and gravity-relative motion, err with respect to the frame of reference implied by their subject is motion responses, believe in sense specific motion percepts, and do not investigate sensory interactions at neurophysiological levels. In addition, much of the target article seems to concern metaphysics rather than empirical science.

We discuss issues raised by the commentators, such as specification in single-energy arrays, task-specific pickup of information, general principles of the ecological approach to perception and action, and how specification may be constrained by the facts of physical relativity. While the commentaries raise many important issues we conclude that they do not undermine our argument that specification exists solely in the global array.

How does evolution grow bigger brains? It has been widely assumed that growth of individual structures and functional systems in response to niche-specific cognitive challenges is the most plausible mechanism for brain expansion in mammals. Comparison of multiple regressions on allometric data for 131 mammalian species, however, suggests that for 9 of 11 brain structures taxonomic and body size factors are less important than covariance of these major structures with each other. Which structure grows biggest is largely predicted by a conserved order of neurogenesis that can be derived from the basic axial structure of the developing brain. This conserved order of neurogenesis predicts the relative scaling not only of gross brain regions like the isocortex or mesencephalon, but also the level of detail of individual thalamic nuclei. Special selection of particular areas for specific functions does occur, but it is a minor factor compared to the large-scale covariance of the whole brain. The idea that enlarged isocortex could be a “spandrel,” a by-product of structural constraints later adapted for various behaviors, contrasts with approaches to selection of particular brain regions for cognitively advanced uses, as is commonly assumed in the case of hominid brain evolution.

Finlay et al. address the importance of developmental constraints in brain size evolution. I discuss some aspects of this view such as the relation of brain size with processing capacity. In particular, I argue that in human evolution there must have been specific selection for increased processing capacity, and as a consequence for increased brain size.