This commentary suggests how Norman's dual control model of vision can be fitted into a broader general model of the control of behaviour by direct (on-line) and indirect (off-line) processes. Some general principles of behavioural organization, development, and competition are described and their specific application to vision is noted.

Opposed to Norman's proposal, processing of affordance is likely to occur not solely in the dorsal stream but also in the ventral stream. Moreover, the dorsal stream might do more than just serve an important role in motor actions. It supports egocentric location coding as well. As such, it would possess a form of representational memory, contrary to Norman's proposal.

Perception, as Gibson described it – picking up information that specifies the real local situation – includes not only perceiving affordances and controlling small movements, but also seeing the large-scale environmental layout and the position/movement of the “ecological self.” If the dorsal cortical system is also responsible for that very significant achievement, its activity must be at least partly conscious.

Self-awareness is thought to be tied to processes of higher-order perspective taking including empathy. These abilities appear to be reserved for humans, great apes, and possibly, dolphins. Recent examinations reveal that both self-awareness and empathy may have origins in the right hemisphere. It is possible that, as in language, lateralization plays a key role in the development of higher-order perspective taking and self-awareness.

The concepts of invariants and cues are useful, as are those of dorsal and ventral streams, but Norman overgeneralizes when interweaving them. Cues are not confined to identification tasks, invariants not to action, and both can be learned.

Whether or not the correspondence of dorsal stream functions to Gibsonian ecological psychology and the ventral stream functions to “constructivism” hold up, the overall goal of capturing a pragmatic realism should not be forgotten.

A primary function of empathy is to help individuals form and maintain social bonds. Empathy should thus occur only when individuals seek to solidify social bonds, and not in response to any opportunity to process others' emotions. Empathy should also involve only certain types of emotion – specifically, emotions that facilitate social bonds – and not any and all types of emotion.

In recent years, explanations of primate cognition highlighted clever arguments, rather than different ability. In the target article, definitions unify, explanations rely on basic nervous system functioning, theory is built on data that fit, and the emphasis is on evolutionary continuities. This commentary describes complexities inherent in the development of empathy that are not accounted for in Preston & de Waal's theory.

Preston & de Waal are understandably cautious in applying their model to autism. They emphasise multiple cognitive impairments in autism, including prefrontal-executive, cerebellar-attention, and amygdala-emotion recognition deficits. Further empirical examination of imitation ability in autism may reveal deficits in the neural and cognitive basis of perception-action mapping that have a specific relation to the empathic deficit.

Attempts to integrate diverse phenomena in terms of common processes are much needed in psychology, but definitional precision is a necessary preliminary to explanation. It is also preferable to use caution in juxtaposing concepts from different realms of discourse.

Research only alluded to by Preston & de Waal (P&deW) indicates the disproportionate involvement of some brain regions in the perception and experience of certain emotions. This suggests that the neural substrate of primitive emotional contagion has some emotion-specific aspects, even if cognitively sophisticated forms of empathy do not. Goals for future research include determining the ways in which empathy is emotion-specific and dependent on overt or covert perception.

Under Preston & de Waal's proposed model, empathy might be regarded as everything that determines the quality of a social relationship. Although the authors provide a useful heuristic for understanding relationships, clinical research efforts with a somewhat narrower focus have provided some additional insights into this topic, which might lead to testable hypotheses regarding the neurobiology of empathy.

To date, a wide range of interdisciplinary scholarship has done little to clarify either the why or the how of empathy. Preston & de Waal (P&deW) attempt to remedy this, although it remains unclear whether empathy consists of two discrete processes, or whether a perceptual and motor component are joined in some sort of behavioral inevitability. Although it is appealing to offer a neuroanatomy of empathy, the present level of neuropsychology may not support such reductionism.

Mammalian brains contain a variety of self-centered socio-emotional systems. An understanding of how they interact with more recent cognitive structures may be essential for understanding empathy. Preston & de Waal have neglected this vast territory of proximal brain issues in their analysis.

The main function of vision in many animals is to control movement. In rodents, some visuomotor acts require the construction of models of the external world while others rely on Gibsonian invariants. Such findings support Norman's dual processing approach but it is not clear that the two types of processing rely on homologs of visual processing streams described in primates.

Our commentary focuses on the functional link between the ventral and dorsal systems implied by Norman, as they relate to overt movement. While issues relating to space perception and size constancy are the primary justification for this dual-process theory, the philosophical extensions of this approach are less consistent with examination of motor control and, in particular, motor learning.

The two modes of visual processing “localizing” versus “identifying” as expressed by four authors in 1967 are more encompassing than the “two visual systems” dichotomies posed by later theorists. Norman's view of parietal cortex functions of vision seems much too narrow.

Norman's identification of a ventral system embodying a constructivist theory of perception is rejected in favor of an ecological theory of perception and perceptual learning. We summarize research showing that a key motivation for the ventral-constructivist connection, percept-percept coupling, confuses perceptual and post-perceptual processes

Empathy represents one of the basic forms of human expression. Empathy evolved to facilitate social behavior. The perception action model, extended to empathy, is an exciting paradigm in which to undertake contemporary cognitive and comparative neuroscience. It renders the perception of events as an active affair, both when watching others, and when performing actions.

Ronan Reilly's connectionist simulation both strengthens and advances the theoretical model presented in my 1991 target article, “Language, Tools, and Brain: The Ontogeny and Phylogeny of Hierarchically Organized Sequential Behavior.” Reilly has tested the whole ontogenetic model with a single simulation study explicitly planned for this purpose. His methodology has established that the various components of the theoretical model imply and are compatible with one another. It has also indicated how learning can actualize a pre-established ontogenetic sequence of combining lingusitic symbols and objects. His simulation suggests that the acquisition of linguistic speech may be facilitated by experience with object manipulation, but not vice versa. This hypothesis can and should be empirically tested through research on behavioral development in the two domains. Finally, Reilly has simulated brain architecture, as well as neural learning. His simulation therefore shows how the development of language and object manipulation can result from an interaction between preprogrammed neural architecture (analogous to network architecture) and experience (analogous to the network's training cycles).