O n f e r e n c e

Short paper 
One of the main research topics I focus on, is how vocabulary acquisition from second 
language (L2) audio-visual input can be enhanced. While the bulk of studies on L2 
vocabulary learning from input have focused on the impact of written text, few studies 
have addressed the potential of audio-visual material for word learning.

---

-259- 
2014 CALL Conference 
LINGUAPOLIS
www.antwerpcall.be 
More particularly, I focus on how to enhance audio-visual material in order to stimulate 
those processes that are required for successful word learning (e.g. noticing, form-
meaning connections). One of the techniques that I included is L2 subtitling or full 
captioning. In order to determine the overall effectiveness of video enhanced with full 
captioning for vocabulary acquisition and investigate the relationship between study 
characteristics (test type and proficiency level) and captioning effectiveness, we 
conducted a meta-analysis (Montero Perez, Van Den Noortgate, & Desmet, 2013). By 
using meta-analytic procedures, we were not only able to quantify the overall 
effectiveness and identify potential moderating effects of study characteristics (Lipsey & 
Wilson, 2001), but a meta-analysis also allows to identify gaps in research and 
methodology which require further research. On the basis of the results of the meta-
analysis, I decided to conduct a series of experimental studies on different types of L2 
subtitles or captions.
Indeed, I have mainly addressed the effects of different visualizations of captions on 
vocabulary acquisition (e.g. Montero Perez, Peters, Clarebout & Desmet, 2014), 
learners’ 
use of captions, and the relationship between use and vocabulary learning effectiveness. 
With type of captioning, I refer to full captioning (the standard example) and captioning 
types in which the unknown words and keywords (i.e. the words essential to the meaning 
of a sentence) are enhanced. The latter include keyword captioning, full captioning with 
highlighted keywords, and glossed keyword captions. Glossed keyword captions provide 
the possibility to access word meaning. I have also investigated the impact of test 
announcement (i.e. forewarning or not forewarning students of upcoming vocabulary 
tests) as an enhancement technique, on vocabulary acquisition and learners’ use of 
captions. In what follows I will focus on a series of methodological challenges that I 
encountered while designing the aforementioned studies and while analyzing research 
findings.
This section is organized around four challenges: I first describe the challenge to find the 
right balance between experimental control and ecological validity, next I focus on the 
use of testing procedures which take into account the complexity of the construct under 
investigation. Finally, challenges are also at the level of data collection techniques and 
data analysis and reporting.
When conducting experimental research and preparing research designs, we need to face 
the constant challenge to find