Between Dec 19, 2024 and Jan 2, 2025, datasets can be submitted to DRUM but will not be processed until after the break. Staff will not be available to answer email during this period, and will not be able to provide DOIs until after Jan 2. If you are in need of a DOI during this period, consider Dryad or OpenICPSR. Submission responses to the UDC may also be delayed during this time.

Browsing by Author "Markant, Julie C."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Effects of Genes on Individual Differences in Executive Function Development in Preschool-Aged Children
    (2015-04-22) Sherman, Samantha J.; Hodel, Amanda S.; Markant, Julie C.; Thomas, Kathleen M.
    Few studies have examined how individual differences in genes related to the brain’s dopamine system impact the development of higher-level cognitive skills in children. Past research with adults has identified that variants of the dopamine transporter gene (DAT-1) are associated with poorer inhibitory control development, including higher impulsivity and risk-taking. Similarly, genetic variability related to COMT, an enzyme that degrades dopamine, predicts working memory abilities in adults. This study evaluated whether individual differences in the DAT-1 VNTR polymorphism and COMT Val158Met polymorphism predicted the development of executive functions (higher order cognitive skills, including working memory, inhibitory control, and attention shifting) at age 5. On tasks requiring inhibitory control (balloon analogue risk task, delay discounting), we found a non-significant relationship between children’s performance and DAT-1 VNTR genotypes. On tasks examining working memory (spatial span, memory search), children homozygous for the Met allele of the COMT Val158Met polymorphism performed more poorly than their peers with a Val allele. Parent report of inhibitory control and working memory development was unrelated to children’s genotypes, highlighting that differences by genotype are not within the clinical range of abnormality. Overall, our results suggest that the COMT polymorphism is associated with similar effects on preschooler’s working memory abilities as reported in adult studies. However, neither DAT-1 VNTR polymorphism predicted inhibitory control development at preschool age, suggesting that additional environmental factors may have a stronger impact on inhibitory control during early childhood.
  • Thumbnail Image
    Item
    Selective attention and Individual differences in infant learning: a comprehensive investigation of exogenous orienting among 7-month-old infants.
    (2010-09) Markant, Julie C.
    Young infants learn incredible amounts of information as they interact with their environment, often without any explicit instruction. Though researchers have identified mechanisms that support learning about regularities in the environment, it is unclear how these mechanisms contend with the massive amount of potentially relevant stimuli available in the world. Selective attention may constrain early learning, since information that is selectively attended may be preferentially processed by learning mechanisms. Previous studies have relied on social-cueing paradigms to examine learning of selectively attended items. However, attention can also be manipulated in a non-social manner using the spatial cueing paradigm, in which salient spatial cues initiate exogenous shifts of attention. Individuals are typically faster to respond to items appearing in the cued location; however, this facilitation is dependent on the timing between the cue and target presentations. Following relatively short cue-target delays, attention is biased towards targets in the cued location, whereas longer delays bias attention towards targets in the non-cued location, a process known as inhibition of return (IOR). This dissertation consists of two studies. Study 1 examined whether selective attention biases modulate 7-month-old infants’ learning of predictable information. Study 2 addressed individual differences in 7-month-old infants’ sensitivity to spatial cues. Specifically, Study 2A examined the consistency of cueing behavior across repeated testing, while Studies 2B and 2C explored behavioral and genetic factors that may influence variation in infants’ sensitivity to spatial cues. Results of Study 1 indicated that spatial cueing modulated selective attention, with enhanced learning of the item that was preferentially attended. Study 2A demonstrated stability in IOR behaviors when using qualitative (categorical) but not quantitative measures. Studies 2B and 2C found that variations in infants’ sensitivity to spatial cues were related to both individual differences in their reactivity to novel stimuli and genetic polymorphisms that affect the dopamine and acetylcholine neurotransmitter systems. These results highlight the complexity of interactions between early attention and learning processes, the wide array of factors that may impact infants’ responses during a basic attention task, and the range of neural systems that are likely involved in early selective attention.