Evidence from optic ataxic patients with bilateral lesions to the superior parietal lobes does not support the view that there are separate planning and control mechanisms located in the IPL and SPL respectively. The aberrant reaches of patients with bilateral SPL damage towards extrafoveal targets seem to suggest a deficit in the selection of appropriate motor programmes rather than a deficit restricted to on-line control.

Glover proposes a planning–control model for the parietal lobe that contrasts with previous formulations that suggest independent mechanisms for perception and action. The planning–control model potentially solves practical functional problems with a proposed independence of perception and action, and offers some new directions for a study of human performance.

I comment on two problems in Glover's account. First, semantic representations are not always available to awareness. Second, some functional properties, the affordances of objects, should be encoded in the dorsal system. Then I argue that the existence of Glover's two types of representations is supported by studies on “object-centered” attention. Furthermore, it foreshadows a nondescriptive causal reference fixing process.

We believe the dichotomy of processes introduced in the target article is highly speculative, because the dichotomy is shaped by the questionable assumption of modularity and the complementary assumption of locality. As a result, the author falls into a line of circular reasoning that biases his analysis of the experimental and neuropsychological data, and weakens the proposed model.

The main issue addressed here concerns the central notion of a forward internal model, through which efficient control and planning are linked together and to the related online predictive error processing. The existence of such a model has strong implications in action production and may question Glover's model.

Which roles are played by subcortical pathways in models of cortical streams for visual processing? Through their thalamic relays, magnocellular (M) and parvocellular (P) projecting ganglion cells send complementary signals to V1, where their outputs are combined in several different ways. The synergic role of M and P cells in vision can be understood by estimating cell response entropy in all domains of interest.

Glover postulates that the inferior parietal lobule (IPL), along with the frontal lobes and basal ganglia, mediates planning, while the superior parietal lobule (SPL), coupled with motor processes in the cerebellum, regulates the control process. We demonstrate that the control process extends beyond the cerebellum and SPL into regions hypothesized to represent planning.

We summarize a number of recent results from our own experiments as well as those from other laboratories. Some of these results support Glover's planning/control dissociation and some are at odds with it. We suggest that the model needs to be further refined and expanded.

Glover offers an account for why some pictorial illusions influence early but not late phases of an action. His proposed corrective control process, however, functions normally in the absence of continuous visual information, suggesting that the stimulus is registered veridically prior to action onset. Here I consider an alternative account, based on differing informational constraints of behaviors (and phases of behaviors).

Several aspects of Glover's planning–control model (PCM) appear incompatible with existing data. Moreover, there is no logical reason to suppose that separate visual representations should be required for the “planning” and “control” of actions in the first place. Although intuitively appealing, the PCM appears to lack strong empirical support.

We report data from an experiment using stimuli designed to differ in their availability for processing by the dorsal visual pathway, but which were equivalent in tasks mediated by the ventral pathway. When movements are made to these stimuli as targets, there are clear effects early in the movement. These effects appear at odds with the planning–control model of Glover.

We argue that planning and control may not be separable entities, either at the behavioural level or at the neurophysiological level. We review studies that show the involvement of superior and inferior parietal cortex in both planning and control. We propose an alternative view to the localization theory put forth by Glover.

The views expressed in the commentaries challenge many of the tenets of the planning–control model as espoused in the target article. This response is aimed at addressing the most serious of these challenges as well as clarifying errors of interpretation. It is argued that the majority of the challenges from brain and behavior, although meritorious, can nonetheless be incorporated within the planning–control model. It is concluded that only some minor revision of the model with regard to anatomy is necessary at this time.

Theories of children's developing understanding of mind tend to emphasize either individualistic processes of theory formation, maturation, or introspection, or the process of enculturation. However, such theories must be able to account for the accumulating evidence of the role of social interaction in the development of social understanding. We propose an alternative account, according to which the development of children's social understanding occurs within triadic interaction involving the child's experience of the world as well as communicative interaction with others about their experience and beliefs (Chapman 1991; 1999). It is through such triadic interaction that children gradually construct knowledge of the world as well as knowledge of other people. We contend that the extent and nature of the social interaction children experience will influence the development of children's social understanding. Increased opportunity to engage in cooperative social interaction and exposure to talk about mental states should facilitate the development of social understanding. We review evidence suggesting that children's understanding of mind develops gradually in the context of social interaction. Therefore, we need a theory of development in this area that accords a fundamental role to social interaction, yet does not assume that children simply adopt socially available knowledge but rather that children construct an understanding of mind within social interaction.

Carpendale & Lewis's (C&L's) theory falls in with an existing set of theories that children's understanding of mind is collaboratively constructed in linguistically mediated social interaction. This social constructivist view needs to be clear about the complementary contributions of the child and of the social environment. I distinguish between the child's individual linguistic ability and the dyad's social communication, proposing that each makes a contribution to theory-of-mind development, differently balanced in different individuals.

Carpendale & Lewis (C&L) rightly emphasise the central role of social interaction in the development of children's understanding of mind. Further support and justification for their theoretical focus are provided by research on advanced reasoning about socio-emotional and socio-motivational processes. Variability in social experience can explain both developmental change and within-age-group differences in such social understanding.

By focusing primarily on communication between adult and child and on adult-set criteria for appropriate action, Carpendale & Lewis's (C&L's) account of the development of social understanding in the epistemic triangle tends toward an enculturation view, while diminishing the role of individuals. What their proposed mechanism fails to acknowledge is that the two agents in the epistemic triangle necessarily have independent perspectives of the object and of each other.

Carpendale & Lewis's (C&L's) proposal of a social interaction account makes clear the need for researchers of all theoretical orientations to get specific about how social experience influences children's developing understanding of mind, but it is premature to reject other theories, such as theory-theory, which also attribute a major role to experience.

A central pillar of Carpendale & Lewis's (C&L's) argument is Wittgenstein's later work on language. I suggest that this support is not as strong as might be wished, and offer an alternative approach to their conclusion that language learning, especially of folk psychology, involves a socially embedded constructivism.

Carpendale & Lewis (C&L) emphasize the importance of viewing language as activity. In this commentary I push further their claim by highlighting how constructions, rather than words, are the appropriate unit of analysis. In addition, I suggest how a discussion of indexicality paves the way for a better understanding of how language provides a powerful tool for children's construction of mind.