L’écriture de mots sur smartphone: Dynamique des processus orthographiques et moteurs

Writing is an essential communication tool, that developed over time through a wide variety of technological tools and modalities. Over the past two decades, cell phones have emerged as one of the most important writing media. The aim of this doctoral dissertation was to deepen our understanding of the cognitive mechanisms involved in smartphone writing. We examined the interaction between orthographic and motor processes, explored the influence of the linguistic factors that constrain their temporal organization and observed the impact of word suggestions on the whole writing processes. Three experimental studies were conducted, using a spelling to dictation task. The first study aimed at assessing the impact of the writing device on orthographic retrieval and motor execution processes. We compared handwriting and smartphone writing in French. The second one investigated the effect of orthographic suggestions on phone-writing. The third, was a cross-linguistic French-Italian experiment that evaluated the effect of orthographic deepness on the use of word suggestions in phone-writing. We recorded errors and online corrections. When a word suggestion was selected, we noted their occurrence and the position in the word at which it was done. Latencies provided information on the processes taking place before movement initiation, while several temporal measures concerned the dynamics of word execution. The data suggests that the timing of word writing relies on a series of trade-offs. The participants took longer to start writing on a smartphone than paper, but letter execution was significantly faster in phone-writing than handwriting. The effect of changing the writing medium therefore produces a temporal reorganization of orthographic and motor processes. Likewise, short words generate higher latencies than long ones, but the former were produced more rapidly than the latter once the writing movements began. These compensations could be due to an attempt of keeping the overall tempo of the writing movements constant. The results also highlight a temporal overlap between orthographic and motor processing, corroborating the idea that word writing results from a cascade of different kinds of processes, such as the one proposed by the APOMI model. Word suggestions decrease the number of errors and online corrections, but they significantly slow down movement execution, especially when the words are short. In addition, phono-graphemic consistency modulates the use of word suggestions, indicating that the technologies that manage the proposal of suggestions could gain in effectiveness if they took into account other variables apart from the word frequency of the user. Word suggestions are mostly selected when writing long words and the writing situation imposes a high cognitive load: a memory load due to the retention of all the letters, a motor load due to the activation of multiple motor programs, and an orthographic load when the words to be written present strong phono-graphemic ambiguities like the ones observed in French orthographically inconsistent words. French writers use significantly more word suggestions than Italian writers showing that the consistency of sound-letter transcriptions modulate the use of word suggestions.