Barresi & Moore fail to provide a satisfactory account for the development of social understanding because of (1) their ambiguous characterization of the relationship between the intentional schema and shared intentional activities, (2) their underestimation of the representational capacities of infants, and (3) their overreliance on the simulationist assumption that understanding others is tantamount to sharing their experience.

The confirmatory nature of the empirical evidence used to establish UG effects in L2 development is considered. Specific issues are also raised concerning the internal validity of Epstein et al.'s findings. It is concluded that the role of UG in adult L2 development will only be established when researchers better understand the interaction between the development of UG-constrained structural knowledge and the development of overall L2 proficiency.

The unification of microscopic and macroscopic models of brain behaviour is of paramount importance and Wright & Liley's target article provides some important groundwork. In this commentary, I propose that a useful approach for the future is to incorporate a developmental perspective into such models. This may be an important constraint, providing a key to understanding the nature of macroscopic measures of brain function such as functional measures like ERP.

Is schedule theory necessary? Or is Killeen (1994a) explaining clever laboratory contrivances that have no necessary relevance to understanding the role of behavior in life? We still await a psychological correspondence principle that can establish a sound basis for this elegant and essentially biological theory of reinforcement schedules.

Zeiler appreciates my organism-centered approach but believes that it issues from the wrong framework and focuses on the wrong phenomena. He is a “sharpener,” I a “leveler”; I believe that the full complexities of organisms in their natural environments should be the terminus, not the origin of our scientific enquiry. The study of schedule performance is oblique but not orthogonal to that terminus, and offers us a secure footing for the next step upward in complexity.

This commentary focuses on whether the full set of categories is available to beginning L2 learners. After critiquing Epstein et al.'s experimental evidence for the presence of functional categories, I outline the results of an experiment involving English speakers learning Japanese as a second language that does indeed point toward the early presence of fuuctional categories.

Barresi & Moore's account has at least two implications for moral psychology. First, it appears to provide support for cognitive theories of moral competence. Second, their claim that the development of social understanding depends upon domain-general changes in cognitive ability appears to oppose the idea that moral competence is under-pinned by a moral module.

For some years there has been a controversy about whether brain state variables such as EEG or neuronal spike trains exhibit chaotic behaviour. Wright & Liley claim that the local dynamics measured by spike trains or local field potentials exhibit chaotic behaviour, but global measures like EEG should be governed by linear dynamics. We propose a different scheme. Based on simulation studies and various experiments, we suggest that the pointwise dimension of EEG time series may provide some valuable information about underlying neuronal generators.

The data reviewed in Barresi & Moore's treatment of social understanding is recast in terms of a model of social intelligence that was advanced some time ago (Gallup 1982). When it comes to their analysis of the behavior of other individuals, most primates (and humans younger than 18 months of age) appear to function as radical behaviorists, whereas chimpanzees and older infants show evidence of becoming primitive cognitive psychologists.

Saccadic eye movements create (at least) two related but distinct problems for the visual system: they cause rapid image motion and a displacement of the retinal image. Although it is often assumed that the motion is too fast to be resolved, this is certainly not the case for low-spatial-frequency images. Recent experiments have suggested that the reason we are unaware of the motion during saccades is because motion channels are selectively suppressed, possibly by suppression of the magno-cellular (but not the parvocellular) pathway. This suppression may explain why there is no sensation of motion during saccades, but it leaves open the problem of perceiving a stable world despite continual image displacements.

Wright & Liley contrast their theory that the global dynamics of the EEG are linear with that of Freeman, who hypothesizes an EEG governed by (nonlinear) deterministic-chaotic dynamics. A “call for further discussion” on the part of the authors is made as to how either theory fits with experimental findings indicating that EEG dynamics are non-linear but stochastic.

Children in a given linguistic environment all uniformly acquire their target language, but adult learners of L2 do not. UG accounts for children's uniform linguistic behavior, but it cannot serve a similar role in accounting for adult learners' linguistic behavior. I argue that Epstein etal.'s study does not answer the question of why L2 learners end up with nonuniform and imperfect linguistic competence in learning a second language.

I would like to emphasize the significance of chaotic dynamics at both local and macroscopic levels in the cortex. The basic notions dealt with in this commentary will be noise-induced order, chaotic “itinerancy” and dissipative structure. Wright & Laley's theory would be partially misleading, since emergent nonlinearity rather than the linearity at even a macroscopic level can actually subserve cortical functions.

The array seen when saccading across a point light source blinking in the dark is displaced in the direction of the saccade. This displacement reflects an abrupt shift of spatiotopic coordinates that precedes the actual eye movement. The extraretinal signal mediating this discrete shift appears to be an oculomotor reference signal, specifying intended eye orientation, that changes discretely before saccades.

Second person intentional relations, involving intentional activities directed at the perceptor, are qualitatively different from first and third person relations. They generate a peculiar, bidirectional kind of intentionality, especially in the realm of visual perception. Systems specialized in dealing with this have been selected by evolution. These systems can be considered to be the evolutionary precursors to the human theory of mind.

L2 learners may access UG principles because these are realized in all natural languages. Since this is not the case for the parametrized aspects of language, parameter setting may be progressively replaced by restructuring mechanisms which are specifically related to the process of representational redescription because L2 learners are not sensitive to the [±] features which define parameters.

The network model of EEG formation has revealed a unified mechanism for disparate EEG phenomena: for various reactions as well as for ontogenetic and phylogenetic differences. EEG rhythmicity was shown to be an external manifestation of the functioning of the intracortical stabilizing system which provides normal informational operations in the cerebral cortex.

Although their thesis is generally sound, Barresi & Moore give insufficient attention to the need for a methodology, whether simulation based or theory-based, for choosing among alternative possible matches of first person and third person information. This choice must be sensitive to contextual information, including past behavior. Moreover, apart from simulation or theory, first person information would not help predict future behavior.

Saccadic suppression is selective, inhibiting only low spatial frequencies. High spatial frequencies need not be inhibited during saccades, for a rapidly moving retina lacks the temporal resolution to detect them. Low spatial frequencies are inhibited by suppressing magnocellular channels. Thus color information is not suppressed, as confirmed in two laboratories. Targets flashed during and just before saccades can be mislocalized because vision normally ignores presaccadic position information.

Epstein et al. take as given that, (1) a hypothetical Universal Grammar (UG) exists that allows children effortlessly to acquire their first language; they then argue (2) that critical or sensitive periods do not block the UG from second language acquisition. Therefore, why can't we all effortlessly “acquire” Tibetan in six months or so? Data concerning the neural bases of language are also noted.