No abstract

The holistic encoding hypothesis (M. J. Farah, K. D. Wilson, M. Drain, & J. N. Tanaka, 1998) proposes that faces are encoded and used in perception and cognition as relatively undifferentiated wholes. A previous study (M. J. Wenger & E. M. Ingvalson, 2002) found very little support for the strong version of this hypothesis and instead found evidence that shifts in decisional criteria may be important. This study provides a replication and stronger test of those findings, demonstrating consistent violations of decisional separability and preservation of informational separability in both immediate perception and delayed recognition.

It has been proposed (see, specifically, M. J. Farah, K. D. Wilson, M. Drain, & J. N. Tanaka, 1998) that human faces are used in cognition as undifferentiated wholes. General recognition theory (GRT; F. G. Ashby & J. T. Townsend, 1986) is used to represent hypotheses regarding the possible sources for the behavioral evidence supporting holistic representation. Specifically, it is suggested that holism can be understood in terms of violations of informational independence, informational separability, or decisional separability, as these constructs are defined in GRT. Stimuli were presented upright, inverted, and in an encoding task that emphasized the meaningful nature of the stimuli. Patterns of performance (recognition hit rates) were consistent with prior studies. However, there were only a handful of violations of informational separability. Instead, consistent violations of decisional separability suggested a decisional basis for holistic effects.

Although cochlear implantation enables some children to attain age-appropriate speech and language development, communicative delays persist in others, and outcomes are quite variable and difficult to predict, even for children implanted early in life. To understand the neurobiological basis of this variability, we used presurgical neural morphological data obtained from MRI of individual pediatric cochlear implant (CI) candidates implanted younger than 3.5 years to predict variability of their speech-perception improvement after surgery. We first compared neuroanatomical density and spatial pattern similarity of CI candidates to that of age-matched children with normal hearing, which allowed us to detail neuroanatomical networks that were either affected or unaffected by auditory deprivation. This information enables us to build machine-learning models to predict the individual children's speech development following CI. We found that regions of the brain that were unaffected by auditory deprivation, in particular the auditory association and cognitive brain regions, produced the highest accuracy, specificity, and sensitivity in patient classification and the most precise prediction results. These findings suggest that brain areas unaffected by auditory deprivation are critical to developing closer to typical speech outcomes. Moreover, the findings suggest that determination of the type of neural reorganization caused by auditory deprivation before implantation is valuable for predicting post-CI language outcomes for young children.