Nonmanuals (henceforth NMs) in sign languages refer to movements of body parts other than hands, such as head, eyebrows, eyes, chin, mouth, shoulder, etc. While in popular perception NMs are ‘facial expressions’, sign language linguists have constantly made attempts to discern the linguistic nature of NMs. Through their research, we now know that NMs play an essential role in the grammar of sign languages around the world. The current volume is an excellent example of such research.

As the editors note in the introduction, the seven papers in the current volume were presented at the Nonmanuals in Sign Languages (NISL) conference, held in 2009 at the University of Frankfurt am Main. They were first published in Sign Language & Linguistics 14 (2011) and have been updated to be included in the current volume. The first paper in the volume is by Sarah Churng, entitled ‘Syntax and prosodic consequences in ASL: Evidence from multiple WH-questions’. Churng notes that multiple wh-questions in American Sign Language (ASL; e.g. YOU EAT WHAT WHY) can be classified into three different constructions, according to the appearance of NMs. Paying attention to the different prosodic characteristics of NMs is important, since they are associated with different semantic interpretations (indicated by three possible answers to the question). Drawing on syntactic analyses of English and Slavic languages, Churng proposes that wh-questions are derived from the structure formed by Parallel Merge via focus movement and remnant movement. She also considers prosodic breaks of NMs and claims that they result from displacements caused by A-bar movement. In the paper ‘Negation in Turkish Sign Language’, Kadir Gökgöz analyzes negation-related NMs in Turkish Sign Language (Türk İşaret Dili, TİD). He argues that the spreading pattern of the NMs is determined by syntactic relations such as c-command and the Spec–head relation. In ‘Eye gaze and verb agreement in German Sign Language’, Jana Hosemann discusses the results of experimental data of German deaf participants who signed sentences in German Sign Language (Deutsche Gebärdensprache, DGS) with plain and agreeing verbs. Even though the sample size was fairly limited, which may be related to inconsistent results among subjects, Hosemann notes a ‘language-specific’ correlation between eye gaze and manual agreement. In the fourth paper, by Donna Lewin & Adam Schembri, entitled ‘Mouth gestures in British Sign Language’, a variety of meanings associated with tongue protrusion (‘th’) in British Sign Language (BSL) are presented with sample data from the authors' ELAN corpus. In her paper, ‘Nonmanual markings for topic constructions in Hong Kong Sign Language’, Felix Sze, carefully reviews previous studies of topic-related constructions in signed and spoken languages. She argues that the classification of topics (‘scene-setting’ and ‘aboutness’) explains the occurrence of NMs in Hong Kong Sign Language (HKSL). In ‘Nonmanuals, semantic operators, domain marking, and the solution to two outstanding puzzles in ASL’, Ronnie Wilbur provides a ‘big picture’ of how different NMs can reflect the syntactic and semantic properties of signed sentences. The focus of Wilbur's paper is to provide a solution to one of the outstanding problems concerning the nature of eyebrow movements. She classifies NMs (brow movements and headshake) into different operator types (monadic and dyadic) and claims that they need to be analyzed separately. The last paper, by Rosalee Wolfe, Peter Cook, John C. McDonald & Jerry Schnepp, is entitled ‘Linguistics as structure in computer animation’. It demonstrates the usefulness of three-dimensional animation for different purposes (such as communicating short messages to the deaf, training sign language interpreters, etc.) and technical challenges that animators face. The authors convincingly explain how linguistic generalization of NMs (such as eyebrow movement) can enhance the communicability of animated signs to the deaf.

The current volume serves as a valuable reference for those who are interested in the linguistic nature of NMs. Though some papers are based on research in its preliminary stages, taken together, the papers should help readers to understand that a variety of important theoretical issues (relevant both to studies of signed and spoken languages) are involved in analyzing NMs. In particular, Churng's paper successfully demonstrates how theoretical concepts proposed in generative syntax can be applied to the analysis of sign languages. Since the goal of the generative enterprise is to consider the universal nature of human languages, works such as Churng's open the possibility that studies of sign languages will provide significant contributions to the theory. Since NMs are often overlooked by those who are not familiar with sign languages produced by native signers, this book is strongly recommended to theoretical linguists with limited or no knowledge of sign languages.

Though many of the articles adopt the Minimalist framework, readers of different theoretical backgrounds will benefit from the book. Topics cover different subfields (syntax, morphology, semantics, pragmatics) with sign language data from different regions (ASL, TİD, BSL, DGS, HKSL). Readers who are unfamiliar with NMs in general might want to begin with Ronnie Wilbur's article. Wilbur's article is outstanding among the papers in the current volume, for its breadth and depth of the discussion. The discussion includes summaries, based on previous work, of grammatical properties of different types of NMs, some of which are topics of the volume's other papers. Though the main purpose of the paper is to advance the syntactic analysis of eyebrow movements and headshakes, it provides a convenient introduction to the issues related to NMs. In contrast, readers who choose to follow the order of the papers (established by the editors) will find that Wilbur's article relates NMs that are individually discussed in the preceding papers. Linguists who have interest in sign language syntax will find Wilbur's review of empirical arguments in previous studies of wh-questions in sign languages beneficial.

Readers will find that many of the papers refer to issues in sign language syntax (such as the derivation of wh-questions) in different sign languages. Currently, however, sign language linguistics sees active development in the field of semantics, and recent work includes semantic analyses of NMs. For example, as shown in Matsuoka & Gajewski (Reference Matsuoka and Gajewski2013), mouth gestures reflect the polarity of the adjective that they co-occur with. Shaffer (Reference Shaffer2004) points out that the continuous manipulation of NMs, combined with manual signs of modality, indicates the degree of the signer's commitment to the proposition in ASL. The general pattern described by Shaffer has been confirmed in Matsuoka et al. (Reference Matsuoka, Hitomi Akahori and Oka2014) with Japanese Sign Language (though different NMs are used for the same purpose). Studies of semantic characteristics of NMs, with a comparison across sign languages, which are not historically related, are ongoing.

Many NMs are difficult to capture in still photos, and hence it is noteworthy that in the volume under review here some authors have provided videotaped examples, which are available for viewing at a dedicated website. There have always been issues of privacy that occur with making examples of signed sentences public. Since NMs mostly appear on the facial area, it is not possible to obscure the image of the informants to protect their identity. That could be why video data or photographs are not available for all papers in this volume. This is a weakness of the book because it would be very helpful for readers (particularly those who are not familiar with sign languages but are seriously interested in theoretical issues) to have access to data by seeing NMs as a part of utterances of native signers.

Finally, it is of particular interest that the current volume finishes with a paper that places special emphasis on how sign language linguistics can contribute to developments in applied engineering. The paper is written so as to be accessible to readers who do not necessarily have the background knowledge of engineering. It will help linguists understand how their research results could be implemented for the development of socially meaningful technology.

In sum, the current volume will benefit not just sign language linguists; theoretical linguists interested in universal properties of natural languages will find this book insightful, too. Though many NMs now have various grammatical functions, it is possible that they have developed from facial gestures. For that reason, the papers in the current volume provides useful information for researchers concerned with the relationship between sign languages and gestures. The breadth of the research topics and the variety of sign languages covered make this volume a useful resource for future research of NMs.