The Effects of Word Identity, Case, and SOA on Word Priming in a Subliminal Context.

It is widely assumed that subliminal word priming is case insensitive and that a short SOA (< 100 ms) is required to observe any effects. Here we attempted to replicate results from an influential study with the inclusion of a longer SOA to re-examine these assumptions. Participants performed a semantic categorisation task on visible word targets that were preceded either 64 or 192 ms by a subliminal prime. The prime and target were either the same or different word and could appear in the same or different case. We confirmed the presence of subliminal word priming (same word < different word reaction times). The word priming effect did not differ when case was the same or different, which supports case insensitive word priming. However, there was a general facilitation effect driven by case (same case < different case). Finally, there was a significant difference between the two SOA conditions; however, there were no interactions between SOA and any other factor, demonstrating that subliminal priming did not differ between short and long SOAs. The results demonstrate that word priming is case insensitive but that there is nevertheless an overall facilitation when words, regardless if they are repeated or not, are presented in the same case. This facilitation in case may reflect modularity in the low-level processing of the visual characteristics of words.

The development of the Poggendorff illusion in typically developing children.

We examined how the strength of the Poggendorff illusion changes with age in typically developing children. To this end, we recruited children aged 6 to 14 years and quantified the degree to which they experienced the illusion. The illusion was strongest in the youngest children and decreased with age logarithmically-reaching adult levels (as established by an earlier study) by 21.6 years, as determined by nonlinear interpolation. We also measured the ability to align two lines together in a nonillusory condition, receptive language, and abstract reasoning to determine whether changes in illusion strength were also associated with these factors. Alignment-matching abilities, receptive language, and abstract reasoning increased with age. However, only receptive language and abstract reasoning were correlated with illusion strength. Abilities in alignment matching were not related to illusion strength and reached adult levels (as established by a previous study) earlier at 14.7 years, as determined by nonlinear interpolation. A multiple regression analysis further revealed that receptive language and abstract reasoning did not contribute beyond their shared variance with age. Based on these findings, we suggest that the illusion is exaggerated in early development and attenuates as low-level and high-level processes mature. The theoretical implications of these findings are discussed.

The strength of the Shepard illusion in children coincides with age and cognitive skills but not perceptual abilities.

We examined how the strength of the Shepard illusion develops with age in typically developing children. To this end, we recruited children between the ages of 6 and 14 years and quantified the degree to which they experienced the illusion. The strength of the illusion increased with age - reaching adult levels by 11.5 years. We also measured abilities in size and shape discrimination, receptive language, and abstract reasoning to determine if changes in illusion strength were also associated with these factors. Abilities in size and shape matching increased with age but did not correlate with the strength of the Shepard illusion. Receptive language and abstract reasoning increased with age and correlated with the strength of the Shepard illusion. However, a multiple regression analysis revealed that they did not contribute beyond their shared variance with age. Based on these findings, we propose that the illusion has a strong acquired component to it and requires the maturation of high-level processes before it is experienced to adult levels at preadolescence.

The development of the size-weight illusion in children coincides with the development of nonverbal cognition rather than motor skills.

We examined how the strength of the size-weight illusion develops with age in typically developing children. To this end, we recruited children aged 5-12 years and quantified the degree to which they experienced the illusion. We hypothesized that the strength of the illusion would increase with age. The results supported this hypothesis. We also measured abilities in manual dexterity, receptive language, and abstract reasoning to determine whether changes in illusion strength were associated with these factors. Manual dexterity and receptive language did not correlate with illusion strength. Conversely, illusion strength and abstract reasoning were tightly coupled with each other. Multiple regression further revealed that age, manual dexterity, and receptive language did not contribute more to the variance in illusion strength beyond children's abilities in abstract reasoning. Taken together, the effects of age on the size-weight illusion appear to be explained by the development of nonverbal cognition. These findings not only inform the literature on child development but also have implications for theoretical explanations on the size-weight illusion. We suggest that the illusion has a strong acquired component to it and that it is strengthened by children's reasoning skills and perhaps an understanding of the world that develops with age.

The Shepard Illusion Is Reduced in Children With an Autism Spectrum Disorder Because of Perceptual Rather Than Attentional Mechanisms.

Earlier studies demonstrate reduced illusion strength in the Shepard illusion in adults and adolescents with an autism spectrum disorder (ASD) and in typically developing (TD) adults with high levels of autistic traits. We measured the strength of the Shepard illusion in ASD and TD children and tested if ten different eye-tracking measurements could predict group differences in illusion strength. The ASD children demonstrated reduced illusion strength relative to the TD group. Despite this, there were no mean differences on any of the eye-tracking measurements between groups. Even though none of the eye-tracking measurements revealed mean differences between the two groups, the degree to which spatial attention was directed toward the standard stimulus, as indexed by the number of saccades within and toward this stimulus, predicted the strength of the illusion in the overall sample. Furthermore, this active scanning of the standard stimulus was found to enhance illusion strength more strongly in the ASD than the TD group. Together, we conclude that scan patterns and the degree to which participants are able to shift between different locations in a visual scene did not account for group differences in illusion strength. Thus, the reduced strength of the Shepard illusion in ASD does not appear to be driven by how attention shifts or is spatially allocated. Rather, differences may relate instead to perceptual mechanisms that integrate visual information. Strategies that may aid ASD individuals to see this illusion more strongly could have them make even more eye movements within and between the stimuli presented in the illusion display.