Central to Hurley's argument is the position that imitation is “automatic” and requires inhibition. The evidence for this is poor. Imitation is intentional, involves active comparison between self and other, and involves new learning to improve self-other likeness. Abnormal imitation behaviour may result from impaired learning rather than disinhibition. Mentalizing may be similarly effortful and dependent upon learning about others.

After offering a brief account of how we understand the shared circuits model (SCM), we divide our response into four sections. First, in section R1, we assess to what extent SCM is committed to an account of the ontogeny and phylogeny of shared circuits. In section R2, we examine doubts raised by several commentators as to whether SCM might be expanded so as to accommodate the mirroring of emotions, sensations, and intransitive actions more generally. Section R3 responds to various criticisms that relate to the account of social-learning Hurley proposes in the target article. We conclude in section R4 by responding to a number of commentators who argued for the limitation of control theory as a framework for studying social cognition.

Our understanding of the sense of taste is largely based on research designed and interpreted in terms of the traditional four “basic” tastes: sweet, sour, salty, and bitter, and now a few more. This concept of basic tastes has no rational definition to test, and thus it has not been tested. As a demonstration, a preliminary attempt to test one common but arbitrary psychophysical definition of basic tastes is included in this article; that the basic tastes are unique in being able to account for other tastes. This definition was falsified in that other stimuli do about as well as the basic words and stimuli. To the extent that this finding might show analogies with other studies of receptor, neural, and psychophysical phenomena, the validity of the century-long literature of the science of taste based on a few “basics” is called into question. The possible origins, meaning, and influence of this concept are discussed. Tests of the model with control studies are suggested in all areas of taste related to basic tastes. As a stronger alternative to the basic tradition, the advantages of the across-fiber pattern model are discussed; it is based on a rational data-based hypothesis, and has survived attempts at falsification. Such “population coding” has found broad acceptance in many neural systems.

There are striking parallels between the basic tastes debate and the debate on human colour categorisation. Colour categories show a remarkable cross-cultural similarity, but at the same the time exhibit seemingly inexplicable large interpersonal variations. Recent results suggest that colour categories are the result of cultural learning constrained by the neural substrate of colour perception.

Types of sensory receptor can only be identified by multidimensional discrimination of a familiar version of a sensed object from variants that disconfound putative types. By that criterion, there is as yet no evidence against just the four classic types of gustatory receptor, for sodium salts, alkaloids, sugars, and proton donors.

Primary, or basic, colors have been discussed for centuries. Over time, three criteria have emerged on their behalf: (a) their physical mixture yielding all other spectral colors, (b) the physiological attunement of receptors or pathways to particular wavelengths, and (c) the etymological history of the color term. These criteria can be applied usefully to taste to clarify issues.

Erickson's treatise intertwines and confuses two major, but separable, issues: whether there are basic tastes and how taste stimuli are encoded. The idea of basic tastes may reflect a natural process of concept formation. By only discussing two spatial coding schemes for taste, Erickson ignores the temporal dimension of taste responses and the contribution of neuronal cooperativity.

Why has the labeled line versus across-fiber pattern debate of taste coding not been resolved? Erickson suggests that the basic tastes concept has no rational definition to test. Similarly, however, taste neuron types, which are fundamental to the across-fiber pattern concept, have not been formally defined, leaving this concept with no rational definition to test. Consequently, the two concepts are largely indistinguishable.

Contrary to the outstanding simplistic view of the taste system, learning studies show a more complex picture. Behavioral data using conditioned taste preference and aversion tasks support the idea that mixtures involve complex interactions between individual taste cues. Evidence from taste conditioned blocking, taste perceptual learning, and taste learned preferences is considered to support such a view. Greater support for research in taste learning and memory is required for a complete understanding of taste recognition.

The physical properties that signify objects differ dramatically, so that the organization of sensory systems must reflect those differences. Although all senses may encode peripheral sensory information using across-fiber firing distributions, an economical coding system for each sense will necessarily differ. An economical code must maximize information about objects, whether they are predators or foods.

The logic of the basic taste concept is discussed in relation to the physiology and psychophysics of color vision. An alternative version of the basic taste model, analogous to opponent-process theory is introduced. The logic of quality naming experiments is clarified.

Recent work on receptor molecules and cells used prototypical sweet, salty, sour, bitter, and umami stimuli. Labeled-line coding was supported, but it remains possible that the molecules and cells could respond to other tastants. Studies with other tastants are needed. The sensory message might contain two codes – one for attraction or aversion, the other, across-fiber patterning of stimulus quality.

Cluster analysis, factor analysis, and multidimensional scaling are not good guides to the number of groups in a data set. In fact, the number of groups may not be a well-defined concept.

The two most popular, yet opposing, models of taste processing, the labeled-line (LL) and across-neuron pattern (ANP) theories, are variants of spatial neural coding. Analyses whose outcomes have been argued to support either theory have sometimes glossed over important caveats and considerations that may drastically impact interpretation. Some of these issues are discussed here.

There is both empirical evidence that supports, and does not support, the four basic tastes, as well as the labeled-line and across-fiber pattern theories. All of these concepts have proven useful to researchers investigating taste coding, and should be appreciated for their heuristic value. Dismissal of any of them is neither supported by evidence nor productive.

Recurrent lexicalization patterns across widely different cultural contexts can provide a window onto common conceptualizations. The cross-linguistic data support the idea that sweet, salt, sour, and bitter are basic tastes. In addition, umami and fatty are likely basic tastes, as well.

Erickson's article links the concept of four “basic” tastes to color perception as a sensory modality with similar problems of categorization. Such problems are also present for odors and olfaction. Olfaction is the sensory modality with the closest physical relationship to taste, and the sense organs of both permanently interact. We discuss the origins and influences of core ideas of the science of smell to add to the discussion of unresolved categorization problems in taste from another, closely related point of view.

Contemporary behavioral and brain scientists consider the existence of so-called basic emotions in a similar way to the one described by Erickson for so-called basic tastes. Commenting on this analogy, I argue that similar basic problems are encountered in both perspectives, and I suggest a potential nonbasic solution that is tested in emotion research (i.e., the appraisal model of emotion).

Gustatory studies are predicated on the existence of basic tastes. Erickson questions this assumption and offers contrary evidence. Although Erickson may conflate certain concepts and demand uncommonly stringent requirements for basic tastes, his thoughtful article reminds us that the basic organization of taste is not yet settled.

Erickson's conclusion that if basic tastes are not appropriate at one level, reference to labeled lines is inappropriate at any level, depends on matters of definition and scope. His population model mirrors Young's theory of color perception. However, there is evidence for distinct pathways to the cortex for two cone-opponent and one achromatic channel. Depending on the use made of key terms, sensory systems may display both across-fiber and labeled-line features.