Verb production by individuals with Down syndrome during narration

Abstract

Background: Despite research identifying verb knowledge as a strong predictor of later syntactic skills in typical development, virtually no research has examined verb development in Down syndrome. Aims: The purpose of this study was to examine verb production (density, diversity, and typetoken ratios) by individuals with Down syndrome in the context of story generation relative to two comparison groups-nonverbal cognitive ability level matches with typical development and chronological age matches with mixed-etiology intellectual disability. Methods and Procedures: Thirty-five participants with Down syndrome (11-21 years), 27 participants with intellectual disability (13-20 years), and 29 participants with typical development (4-6 years) completed a narrative story generation task. Transcripts were coded and analyzed for verb production. Outcomes and Results: Examining overall verb production, participants with Down syndrome produced narratives with less verb density than participants with typical development and had smaller verb type-token ratios than participants with intellectual disability. Upon examining lexical verb production, participants with Down syndrome produced narratives with less lexical verb density than participants with typical development.

A Review Paper on the Syntactic Abilities of Individuals with Down Syndrome

“…It is documented that DS individuals produced fewer or no utterances with verbs overall relative to TD population, although this result was found statistically significant only at higher lexical levels (of 251 -400 words) (Galeote et al, 2018). At this point, we should mention that although individuals with DS may have a large number of verbs in their vocabularies, with greater diversity of lexical verbs, however, they did not use them regularly (Loveall et al, 2019). Moreover, they were able to produce transitional forms and made significantly greater use of some of them, for example formulas and dummy element productions, than TDC in some cases (Zampini & D'Odorico, 2011).…”

“…The data from the studies presented, showed a disadvantage of the DS population in syntactic processing, at both production (Hesketh & Chapman, 1998;Vicari et al, 2000;Ring & Clahsen, 2005a;Tsakiridou, 2006;Joffe & Varlokosta, 2007;Stathopoulou, 2007;Caselli et al, 2008;Zampini & D'Odorico, 2011;Andreou, 2013;Bello et al, 2014;Koizumi et al, 2019;Loveall et al, 2019) and comprehension (Chapman et al, 1991(Chapman et al, , 2002Rondal & Comblain, 1996;Vicari et al, 2000;Perovic, 2001Perovic, , 2006aRing & Clahsen, 2005a, 2005bAndreou, 2013;Bello et al, 2014;Joffe & Varlokosta, 2007;Sanoudaki & Varlokosta, 2014;Loveall et al, 2016;Witecy & Penke, 2017;Polišenská et al, 2018;Koizumi et al, 2019) levels, compared to typically developing individuals. This disadvantage has been interpreted by the researchers as either delayed or following a completely different pathway.…”

“…Most studies in the relevant literature have been carried out with English-speaking individuals, and an important question that arises is whether their results apply for other languages. For this reason, this review paper included studies from various countries with different speaking languages, thus giving information on the language abilities and more specifically on the syntactic abilities, of the DS population in English (Bridges & Smith, 1984;Laws & Bishop, 2003;Joffe & Varlokosta, 2007), German (Witecy & Penke, 2017;Penke, 2018), Italian (Fabbretti et al, 1997;Vicari et al, 2000;Caselli et al, 2008;Zampini & D'Odorico, 2011;Bello et al, 2014), Spanish (Checa et al, 2016;Galeote et al, 2013Galeote et al, , 2018, French (Facon & Magis, 2019), Slovak (Polišenská et al, 2018), Greek (Tsakiridou, 2006;Stathopoulou, 2007;Andreou, 2013;Sanoudaki & Varlokosta, 2014), Serbo-Croatian (Perovic, 2006b), American (Hesketh & Chapman, 1998;Thordardottir et al, 2002;Chapman et al, 2002;Chapman, 2006;Michael et al, 2012;Loveall et al, 2016Loveall et al, , 2019; among others) and Japanese (Koizumi et al, 2019). No restriction was mooted during the selection process of the studies and therefore this review provides evidence from a variety of languages in addition to English, giving the opportunity for comparisons and further knowledge on the syntactic performance of this population in various languages.…”

“…Some studies show that individuals with DS produce fewer verbs overall relative to TD children, whether matched on MLU (Hesketh & Chapman, 1998), receptive vocabulary (Michael et al, 2012), or nonverbal cognitive ability levels. Loveall et al (2019) examined verb production by individuals with DS relative to both TD peers matched by nonverbal cognitive ability level and to individuals with mixed-etiology ID of other origins matched by chronological age. Results of this study indicated that participants with DS produced narratives with less verb density than participants with TD, they had smaller verb type-token ratios than participants with intellectual disability and they demonstrated relatively strong verb diversity.…”

“…However, Grela (2002) failed to find significant differences between individuals with DS and TD children matched on MLU in their production of verbs, probably due to differences in the elicitation materials used across studies. Hesketh & Chapman (1998), Michael et al (2012) and Loveall et al (2019) all used narrative tasks, but Grela's (2002) data included language transcripts. Also, differences may occur due to different CA, as the participants in the study of Grela (2002) may not have had sophisticated enough expressive language to reveal differences in verb use.…”