Comparing language samples of Bangla speakers using a colour photograph and a black-and-white line drawing

A comprehensive aphasia assessment is necessary to diagnose the type and severity of aphasia differentially and guide appropriate interventions. One component of an aphasia assessment is the picture description task (PDT), designed to probe spontaneous speech fluency and information content. Most aphasia assessments use black-and-white line drawings (LD) to elicit spontaneous language samples from people with aphasia (PWA). However, recent studies reported two visuographic variables: (1) colour (over black and white) and (2) photograph (over LD), that tended to encourage easier and faster comprehension and increased overall naturalistic language production from neurologically healthy individuals as well as PWA. Additionally, a suitable stimulus for a PDT should always be culturally relevant to the target population. Therefore, we suggest that a new PDT must include a culturally appropriate colour photograph (CP).

To investigate if a culturally appropriate CP elicits longer and more complex utterances than a culturally appropriate black-and-white LD from neurologically healthy native Bangla speakers.

A total of 30 participants (mean age = 36.03 years) were recruited based on self-reports of no known impairments in cognition, language, vision and hearing. All were of middle socioeconomic status with at least 12 years of formal education. A culturally appropriate CP was selected showing multiple characters performing various functions. Later, an artist prepared the black-and-white LD of that CP. The elicited language samples using these two pictures were transcribed and coded following preset transcription and coding guidelines. The transcribed samples were further analysed using the Bangla adaptation of Systematic Analysis of Language Transcripts (SALT) software. To identify the differences in language production between these two picture types, investigators used four measurement variables: mean length of utterances (MLU), complexity index (CI), total number of words (TNW) and words per minute (WPM).

Of the four measures, only MLU showed a statistically significant difference between the CP and the black-and-white LD. CI demonstrated a strong correlation with MLU for the CP, which indicates that the participants who produced higher MLU for the CP also produced a higher CI for the CP. There were no significant differences between the two picture types for CI, TNW and WPM.

This study found that the grammatical complexity, as measured by MLU, of spontaneous language production of neurologically healthy adults was higher when a CP was used in a PDT. A CP may also be beneficial for PWA to produce complex language samples. What this paper adds What is already known on the subject There are studies on neurologically healthy individuals as well as on PWA that identified the impact of using different visuographic variables (colour and photograph) separately, which enhanced the picture comprehension and improved performances on associated language production tasks. To our knowledge, no studies have identified the combined impact of these two visuographic variables on spontaneous language production. Therefore, this initial study on neurologically healthy Bangla adults reports the impact of using a CP as a stimulus item for a PDT task to elicit spontaneous language samples. What this paper adds to existing knowledge This study reports that using a culturally appropriate CP for a PDT enhances the grammatical complexity of spontaneous language production of neurologically healthy adults. To our knowledge, this is the first study in Bangla that used the MLU as a measurement variable to analyse adults' spontaneous language production. What are the potential or actual clinical implications of this work? The development of future aphasia assessments should consider incorporating CPs as stimuli for PDTs, which may guide speech-language pathologists to provide accurate diagnoses for aphasia and related language disorders.