“Talk to me with left, right, and angles”: Lexical entrainment in spoken H ebrew dialogue (2021)

Abstract: It has been well-documented for several languages that human interlocutors tend to adapt their linguistic productions to become more similar to each other. This behavior, known as entrainment, affects lexical choice as well, both with regard to specific words, such as referring expressions, and overall style. We offer what we believe to be the first investigation of such lexical entrainment in Hebrew. Using two existing measures, we analyze Hebrew speakers interacting in a Map Task, a popular experimental setup, and find rich evidence of lexical entrainment. Analyzing speaker pairs by the combination of their genders as well as speakers by their individual gender, we find no clear pattern of differences. We do, however, find that speakers in a position of less power entrain more than those with greater power, which matches theoretical accounts. Overall, our results mostly accord with those for American English, with a lack of entrainment on hedge words being the main difference.

## introduction entrainment, also known as accommodation or alignment, is a widespread phenomenon in human interaction which leads interlocutors to adapt to each other to become more similar. it has been found for a variety of linguistic dimensions, including prosody @xcite , phonetics @xcite , syntax @xcite , and lexical choice @xcite . lexical entrainment has been studied for several types of lexical choices from specific sets of words -such as referring expressions @xcite , high-frequency words and taskrelated words @xcite , as well as hedge and cue phrases @xcite -to the wider linguistic style @xcite . this motivates us to consider both specific word sets and overall language use here. importantly, there are correlations between lexical entrainment and interesting aspects of the conversation. these include task success for both speaker pairs @xcite and groups @xcite , conversation flow and perceived naturalness @xcite , as well as power differences between the speakers @xcite . this suggests practical applications and has led to the development of entraining natural language generators in dutch @xcite , german @xcite , and american english and european portuguese @xcite , among others. to the best of our knowledge, there has not been any systematic research on lexical entrainment in hebrew or any other semitic language. previous studies analyzing lexical choice in semitic languages focus on borrowing and code-switching, for instance between arabic and english @xcite and arabic and hebrew @xcite . given the important social role of entrainment and its potential applications, our study provides an important contribution by presenting the first analysis of lexical entrainment in hebrew. this helps identify variations in how the behavior manifests in different linguistic and cultural contexts. we note that in a recently published study @xcite , we analyzed acoustic-prosodic entrainment in hebrew for the same data. together, these two papers provide a broad investigation of entrainment for this novel language context. ## corpus in this study, we analyze the open university of israel map task corpus (matacop) @xcite of dyadic, hebrew conversations, modeled after the hcrc map task corpus @xcite . each participant was given a map with la-beled landmarks, some of them shared with the partner's map, some unique. the map of one participant in a pair, the leader, contained a path among the landmarks. it was their task to describe the path so their partner, the follower, could reproduce it. all speaker pairs discussed the same two pairs of corresponding maps, with either speaker acting as a leader for one map and as a follower for the other. we refer to whole conversations as sessions and to each of the two parts as tasks. matacop contains about six hours of conversations between 32 speakers, all of them fluent in hebrew. there are six female, six mixed, and four male pairs. most of the paired speakers were acquainted prior to the experiment. we analyze the influence of this aspect of our data in section 5.7. further details on the level of familiarity is provided in appendix b. for more details on the corpus in general, see @xcite . ## transcription, tokenization, and lemmatization matacop is fully transcribed. the phoneme set consists of the five vowels @xcite and 21 consonants of modern hebrew. the pharyngeal [q] and the glottal [p] are not represented. the phonetic representation removes ambiguity that occurs in hebrew orthography. for example, the grapheme ‫למה‬ is represented with two different transcriptions, le-ma "what for?" and lama "why?". in this paper, we use romanization of hebrew to transliterate hebrew words. tokenization, on the other hand, generally follows standard hebrew orthography. for instance, proclitics (such as mi-"from") were transcribed attached to the subsequent word (e.g., mi-nekuda "from point"). however, in case a silent pause or other disfluency occurred between a clitic and the subsequent word, the clitic was transcribed separately, as in mi-nekuda "from point". in total, this yields 50075 tokens for the corpus. due to hebrew's rich morphology, many of the words in our corpus appear in a variety of grammatical forms, such as agol "round.m.sg", agula "round.f.sg", agul-im "round.m.pl", and ha-agol "the-round". we use a manually created list of grammatical forms for each lemma to lemmatize and count occurrences per lemma. 1 overall, there are 1,038 lemmas and 2,179 other grammatical forms. 1 all word lists we use here can be downloaded at openu.ac.il/en/academicstudies/matacop/pages/default.aspx. ## lexical entrainment measures we measure the lexical similarity of speakers' utterances per session (or task, where noted) using two previously established measures, one for a specific set of words w , one for the overall productions. per word @xmath0, the first measure determines cnt s (w), the number of times w was uttered by s, and ttl s , the total number of words uttered by s. similarity between a pair of speakers s 1 , s 2 is then defined based on the absolute difference of the fractions per word, as @xcite proposed this measure for high-frequency words. note that it is symmetric. the second measure was originally proposed by @xcite to compare tones and break indices (tobi). for it, we construct a trigram language model for each speaker from their utterances, using srilm @xcite . the measure sim 2 (s 1 , s 2 ) is then defined as the negated perplexity of using the language model for s 1 to predict all utterances of s 2 , computed with srilm. low perplexity indicates that the model for s 1 is a good representation of the utterances of s 2 . in this case, the phrases used by s 2 are essentially a subset of those used by s 1 . we interpret this as entrainment of s 1 towards s 2 as it signals that s 1 incorporated s 2 's phrases into their own. conversely, high perplexity indicates a lack of entrainment. this is why we use negated perplexity for sim 2 . note that this measure is asymmetric. for a symmetric version, we simply add the asymmetric values for both directions, following @xcite . to determine whether significant entrainment is present, we follow @xcite . each similarity value sim i (s 1 , s 2 ) for a speaker s 1 with their partner s 2 is compared with the weighted average similarity of s 1 with non-partners, using paired student's t-tests. non-partners must have the same gender as s 2 and their partners must have the same gender as s 1 . for similarity per task, nonpartners must also be talking about the same map and have the same role as s 2 . non-partners are weighted by how closely their language model's entropy, computed using srilm, matches that of the actual partner (absolute differences). this is meant to account for the effect that the richness of a speaker's lexical inventory has on our measures and follows @xcite . ## discussion in this first analysis of lexical entrainment in hebrew, using two existing measures, we find substantial evidence of entrainment both on specific groups of words and overall language use. speakers entrained on the 25 most frequent lemmas in the corpus, a result that matches findings on english corpora of telephone conversations @xcite , deceptive interviews @xcite , and task-oriented, multi-party interactions @xcite . the broadest and most significant evidence of entrainment we find is for directional terms and the geometric terms to describe the path. in fact, in some cases speakers actively requested entrainment, as in: a azov et ha-sinus-im daber iti besmol-a yemin-a ve-be-zaviy-ot "uh leave the sines, talk to me with to-the-left, to-the-right, and with angles". our results match previous ones for referring expressions @xcite and "project words" @xcite in english. contrary to @xcite , who found the strongest evidence of lexical entrainment for hedge words, we find no entrainment for these. this may be because hebrew speech patterns tend to be very "direct" @xcite 2), more so than english ones @xcite , so hedges might be culturally less appropriate. we do not find that speakers entrain on an imperative mode of speaking. this may be due to data sparsity, though, as imperatives constitute only 1.3% of all tokens (see appendix a) despite the experimental setting facilitating their use. studies of syntactic alignment, e.g., by @xcite , have found that english speakers adopt syntactic choices from their interlocutors. a broader investigation of this is needed for hebrew. our results for entrainment on overall productions -how well speakers' language models fit their interlocutors' productions -match prior results for english. @xcite found this measure to be significant for both task-oriented dialogs and telephone conversations. but unlike us, they found the results for this measure to be more significant than those for the 25 most frequent terms. our results reveal no clear pattern of differences between the gender pairs. the number of entrainment targets and significance levels for female, male, and mixed pairs are comparable (marginally weaker results for male pairs might be partially attributable to a smaller sample size). direct comparisons between the gender pairs also do not reveal any significant differences for any of our measures. neither does the comparison between individual speakers based on their gender, using the asymmetric version of our measure for overall productions. similar analyses for acoustic entrainment in english have sometimes found differences based on speaker gender @xcite and sometimes not @xcite . in our own analysis of acoustic entrainment in the same hebrew corpus @xcite , we also found no difference based on speaker gender. the only study of the effect of gender on lexical entrainment we are aware of was for human-robot interactions and found that female speakers exhibited a greater degree of entrainment to the robot interlocutor than males did @xcite . speakers in subordinate roles are predicted to entrain more than those in power @xcite . this has been confirmed for lexical entrainment in english @xcite and we find the same here. followers, having less power due to their dependency on information from the leaders, entrain more than leaders with regard to their overall productions. conversely, for directional terms alone, @xcite found that followers had greater influence on the terminology, that is, leaders adopted followers' terms more often than vice versa. it is worth repeating that speakers in our corpus were acquainted prior to their participation in the experiment. there is little prior research on the impact of this factor. for acoustic-prosodic entrainment, truong and heylen (2012) find that unacquainted speakers exhibit more entrainment while @xcite report an example with the opposite trend. the analysis of our own data indicates that familiarity has at least some influence, specifically for entrainment on overall productions. however, for hedge words the difference between high and low familiarity pairs is so insignificant (t(14) = 0.50, @xmath1.62) that we do not believe familiarity explains the difference between our results and those for unacquainted english speakers. overall, we find that lexical entrainment in our hebrew corpus is very much comparable to prior results for english. the only notable difference is the lack of entrainment on hedge words which, as we noted above, may be due to cultural differences. future research should investigate additional conversational settings in hebrew, including with unacquainted speakers.