My favorite graph: Individual differences in cochlear implant outcomes

The Childhood Development after Cochlear Implantation (CDaCI) study was a pivotal study of language development in children receiving cochlear implants (CIs) in the early 2000s. The main findings were that children receiving CIs developed better receptive and expressive language skills than would be predicted if they had not undergone implantation, presented in Niparko etal. (2010). Figure 1 from that publication showed the trajectories of language improvements after cochlear implantation, represented as spaghetti plots for individual CI children, relative to a group of normal-hearing (NH) peers. Figure 1 demonstrated enormous individual differences in receptive and expressive language scores for the CI children, spanning from zero (the minimal performance possible) to the maximal performance demonstrated by NH peers. Most research has focused on the significant group effect findings (CI versus NH), while neglecting a deep dive into the factors underlying the individual differences across participants. Yet, Figure 1 from Niparko et al. (2010) remains a valuable figure that has motivated work from our research groups to explain and predict CI outcomes, the longitudinal trajectories of outcomes following implantation, and sources of variability, which will be discussed at a high level and related back to Figure 1 by Niparko et al. (2010).