This experimental study aims to determine whether the Symmetry Condition proposed by Battison (1978) is a general cognitive constraint or a language-specific constraint. The main hypothesis was that the Symmetry Condition, which constrains the forms of signs and gestures, is a non-linguistic constraint. To test the hypothesis, the researchers compared the degree of symmetry in balanced signs and co-speech representational gestures. Using t-test, the result shows no significant evidence that indicates differences in the degree of violation of the Symmetry Condition between signs and speech-accompanying representational gestures. In other words, the symmetry degree in the handshapes of sign language and spontaneous co-speech gestures were almost identical. This finding illustrates that the Symmetry Condition does not necessarily belong to Sign Language Phonology. The authors also suggested in brief that the constraint is cognitive-based which encourages the symmetrical use of hands for representational purposes and accepts bi-classifier constructions.
The participants choice, signers and gesturers, was based on the tradition that sign languages should be constrained by the Symmetry Condition from sign language phonology while co-speech gestures should be governed by the linguistic-unrelated semiotic principals. To put it simply, if the experimental result indicates nearly symmetrical degree to which signs and gestures obey the Symmetry Condition, it infers that their underlying target representations are governed by the same condition. Besides, the shared condition would not be the Symmetry Condition because gestures do not constitute a phonological system. Indeed, the experiment found symmetrical degree for signs and gestures. This article later proposed in short that the human cognitive system offers a sign language constraint because the mind allows bi-classifier constructions while the Symmetry Condition is only applicable for symmetrical movements of two hands with one concept.
Regarding characteristics of the 10 participants, 4 of them are native Netherlands Sign Language signers (NGT) while 6 of them are native Dutch speakers. The authors did not provide any further demographic information about the subjects such as age which is a crucial variable to be monitored. Thus, it is uncertain whether they have a huge age range which might negatively affect the validity of the experiment since age is a contributing factor that causes changes in sign handshapes and sign frequency (Stamp et al., 2014). As a huge age gap would be a confounding variable, adding more demographic information about the subjects would strengthen the internal validity. Moreover, keeping an equal number of the two sample groups would have aided the data analysis to avoid sample size being too small. However, the article vehemently holds that the sample size is large enough for representation, given that the samples were able to capture two differences which attribute to sign phonology. The data used were adequate to support the extra findings that the probability of handshapes sloppiness is higher in gestures than in signs and that signs have a higher chance to make body contact than gestures.
Regarding the experimental procedure, the participants were given short cartoon animation and asked to narrate the scenes through story-telling. Narratives with balanced signs and co-speech representational gestures data were collected from 2 cartoon scenes for analysis. Since the Dutch speakers and the NGT signers were exposed to the same animation, this variable control procedure improves the internal validity. As for data analysis, a two-tailed independent sample t-test was used as an inferential statistic that compared the mean proportions for the sign and gesture data respectively. Although the chosen statistical method was appropriate, the significant level of the test, independent variables, and dependent variable were not clearly stated. Alongside the missing statistical information, the writers summarised the data in two tables without describing any significant statistical findings for readers to understand such as the comparison between t-value and p-value. Therefore, the result section was not very well-organised and readers without profound knowledge about inferential statistics might find it hard to comprehend. However, the headings and table legends contained sufficient description for the given statistical data which aids the understanding of the research result.
Overall, this article began with a clear outline with fundamental knowledge provided about the signs and gestures data selection and coding methods. While the research has its merit, the result description and statistics should be clearly written for the ease of comprehension. Moreover, more demographic information about the participants could be provided and the number of subjects could be kept equal to improve internal validity. The proposal that sign languages are constrained by cognitive constraints also warrants further investigation due to limited evidence provided.This non-hypothesis-driven study was designed to introduce ‘rhythm ratio’ which measures variations in phrasal rhythmic patterns of sign language. The ratio is calculated by dividing lexical sign duration by transitional movements duration. Another goal of the research is to use rhythm ratio to investigate how much contribution sociolinguistic factors such as gender, age, and sign variety made to such variations by rhythmic analysis of groups and individual American Sign Language (ASL) narratives. The results attest that rhythm ratio could be a potential methodology to capture rhythmic patterns of ASL with different sign varieties. In addition, its findings demonstrate that the three suggested sociolinguistic factors give rise to ASL rhythmic variations, with age being the most foreseeable cause for such variations, followed by gender, and then sign variety such as Black ASL. The authors concluded that prosodic patterns made by signers were served as a cue that they are representatives of different communities.
Regarding previous literature, the one study involving phrasal rhythm was the study of Swiss German Sign Language which researchers found that side-to-side leans mark rhythmic unites when signers were standing (Boyes Braem, 1999). Considering the fact that very little research has been done specifically on transitional movement in sign language, it motivates the authors to expand the use of rhythmic patterns to measure sign variation and fill the gap in the literature.
In this experiment, 24 ASL signers were recruited and put in groups according to their age (young and old), gender (male and female), and sign variety (Black ASL and Mainstream ASL). However, there was one unrepresentative sample being excluded within the 24 participants due to her late SL acquisition. The researchers did so because this sample should not be used to make any inference regarding prosodic patterns about the population to prevent selection bias. Within the sample, 4 men (0.67) and 2 women (0.33) were assigned to older (mean age: 63.4) Black ASL group while 3 men (0.43) and 4 women (0.57) were in the older mainstream ASL group. For younger groups (mean age: 25.6), the Black ASL group consists of 3 males (0.60) and 2 females (0.40), and the mainstream ASL group has 2 males (0.40) and 3 females (0.60). Therein lies the problem of the sample size being too size and not well-distributed. The sample number for older Black ASL women signers, in particular, is relatively low. Therefore, the research results could only remain suggestive as described by the writers.
Regarding the experimental procedure, the participants had to watch one of the two selected Disney carton and retell the story afterwards so individual data can be collected. Then, the gathered narratives were retold to other signers according to their race and age so group variation can be analysed. The tool utilised for sign language annotations with the 23 narratives was ELAN developed by The Language Archive in 2020 (Perniss, 2015). This instrument was used by 2 independent annotators to measure the three most crucial cues for analysing rhythmic patterns which are sign duration, transition duration, and phrasal position. During the annotation process, there was disagreements between the annotators regarding the analysis for Utterances, Intonational Phrase, sign duration, and transitional duration. However, all debates were addressed by recoding and re-evaluating part of the data which increases the reliability of the experiment.
For some significant findings, it includes that older and younger Black ASL female signers showed a significant prosodic difference regarding sign rate and duration than other groups caused by desegregation in deaf school and an advocacy of mainstream education for deaf children. Other main outcome includes that the young Black signers demonstrated greater distinction on sign rate, sign duration, and transitional duration than other young groups. The discussion session mentioned that this could be due to a higher likelihood for young Black ASL signers to show early sign language changes and use mixed and signed ASL varieties before prevalence. All these highlight that rhythm ratio allows sociolinguistic factors to be considered as causes for phrasal variation in sign language.
Overall, this article is well-structured. The constant comparison between sign language and spoken helps readers understand the complex concept of prosody. Additionally, removing unrepresentative sample to avoid selection bias reduces threats to internal validity while re-evaluating data based on disagreement between annotators increases data reliability. Nevertheless, a larger sample for categorical data analysis would have aided the experiment, particularly for searching possible interactions between gender, age, and sign variety. As for data presentation, all figures and tables were used appropriately with clear figure legends and titles.