Disengaging attention sets the temporal limit of attentive tracking

At first sight, recent studies investigating the temporal limits of attentive tracking show contradictory outcomes. Attentively tracking an object in an ambiguous apparent motion display can have an upper limit of around 0.4 revolutions per second (rps) [Horowitz, T. S., Holcombe, A. O., Wolfe, J. M., Arsenio, H. C., & DiMase, J. S. (2004). Attentional pursuit is faster than attentional saccade. Journal of Vision, 4, 585-603] or 1 rps [Verstraten, F. A., Cavanagh, P., & Labianca, A. T. (2000). Limits of attentive tracking reveal temporal properties of attention. Vision Research, 40, 3651-3664.]. Here, we demonstrate that this difference depends on presentation conditions: an important determinant for the temporal limit of attentive tracking appears to be the duty cycle. Tracking performance at high(er) rates decreases to chance with increasing duty cycle, while at low rates duty cycle hardly has an effect on performance. Results are discussed in terms of (dis)engagement of attention

Disengaging attention sets the temporal limit of attentive tracking

At first sight, recent studies investigating the temporal limits of attentive tracking show contradictory outcomes. Attentively tracking an object in an ambiguous apparent motion display can have an upper limit of around 0.4 revolutions per second (rps) [Horowitz, T. S., Holcombe, A. O., Wolfe, J. M., Arsenio, H. C., & DiMase, J. S. (2004). Attentional pursuit is faster than attentional saccade. Journal of Vision, 4, 585-603] or 1 rps [Verstraten, F. A., Cavanagh, P., & Labianca, A. T. (2000). Limits of attentive tracking reveal temporal properties of attention. Vision Research, 40, 3651-3664.]. Here, we demonstrate that this difference depends on presentation conditions: an important determinant for the temporal limit of attentive tracking appears to be the duty cycle. Tracking performance at high(er) rates decreases to chance with increasing duty cycle, while at low rates duty cycle hardly has an effect on performance. Results are discussed in terms of (dis)engagement of attention

Disengaging attention sets the temporal limit of attentive tracking

At first sight, recent studies investigating the temporal limits of attentive tracking show contradictory outcomes. Attentively tracking an object in an ambiguous apparent motion display can have an upper limit of around 0.4 revolutions per second (rps) [Horowitz, T. S., Holcombe, A. O., Wolfe, J. M., Arsenio, H. C., & DiMase, J. S. (2004). Attentional pursuit is faster than attentional saccade. Journal of Vision, 4, 585-603] or 1 rps [Verstraten, F. A., Cavanagh, P., & Labianca, A. T. (2000). Limits of attentive tracking reveal temporal properties of attention. Vision Research, 40, 3651-3664.]. Here, we demonstrate that this difference depends on presentation conditions: an important determinant for the temporal limit of attentive tracking appears to be the duty cycle. Tracking performance at high(er) rates decreases to chance with increasing duty cycle, while at low rates duty cycle hardly has an effect on performance. Results are discussed in terms of (dis)engagement of attention

Dominant-negative ALK2 allele associates with congenital heart defects

BACKGROUND: Serious congenital heart defects occur as a result of improper atrioventricular septum (AVS) development during embryogenesis. Despite extensive knowledge of the genetic control of AVS development, few genetic lesions have been identified that are responsible for AVS-associated congenital heart defects. METHODS AND RESULTS: We sequenced 32 genes known to be important in AVS development in patients with AVS defects and identified 11 novel coding single-nucleotide polymorphisms that are predicted to impair protein function. We focused on variants identified in the bone morphogenetic protein receptor, ALK2, and subjected 2 identified variants to functional analysis. The coding single-nucleotide polymorphisms R307L and L343P are heterozygous missense substitutions and were each identified in single individuals. The L343P allele had impaired functional activity as measured by in vitro kinase and bone morphogenetic proteinspecific transcriptional response assays and dominant-interfering activity in vivo. In vivo analysis of zebrafish embryos injected with ALK2 L343P RNA revealed improper atrioventricular canal formation. CONCLUSION: These data identify the dominant-negative allele ALK2 L343P in a patient with AVS defects