Martin Verner

Cortical oxygen consumption in mental arithmetic as a function of task difficulty: a near-infrared spectroscopy approach

The present study investigated changes in cortical oxygenation during mental arithmetic using near-infrared spectroscopy (NIRS). Twenty-nine male volunteers were examined using a 52-channel continuous wave system for analyzing activity in prefrontal areas. With the help of a probabilistic mapping method, three regions of interest (ROIs) on each hemisphere were defined: The inferior frontal gyri (IFG), the middle frontal gyri (MFG), and the superior frontal gyri (SFG). Oxygenation as an indicator of functional brain activation was compared over the three ROI and two levels of arithmetic task difficulty (simple and complex additions). In contrast to most previous studies using fMRI or NIRS, in the present study arithmetic tasks were presented verbally in analogue to many daily life situations. With respect to task difficulty, more complex addition tasks led to higher oxygenation in all defined ROI except in the left IFG compared to simple addition tasks. When compared to the channel positions covering different gyri of the temporal lobe, the observed sensitivity to task complexity was found to be restricted to the specified ROIs. As to the comparison of ROIs, the highest oxygenation was found in the IFG, while MFG and SFG showed significantly less activation compared to IFG. The present cognitive-neuroscience approach demonstrated that NIRS is a suitable and highly feasible research tool for investigating and quantifying neural effects of increasing arithmetic task difficulty.

The effect of nontemporal stimulus size on perceived duration as assessed by the method of reproduction

Perceived duration is assumed to be positively related to nontemporal stimulus magnitude. Most recently, the finding that larger stimuli are perceived to last longer has been challenged to represent a mere decisional bias induced by the use of comparative duration judgments. Therefore, in the present study, the method of temporal reproduction was applied as a psychophysical procedure to quantify perceived duration. Another major goal was to investigate the influence of attention on the effect of visual stimulus size on perceived duration. For this purpose, an additional dual-task paradigm was employed. Our results not only converged with previous findings in demonstrating a functional positive relationship between nontemporal stimulus size and perceived duration, but also showed that the effect of stimulus size on perceived duration was not confined to comparative duration judgments. Furthermore, the effect of stimulus size proved to be independent of attentional resources allocated to stimulus size; nontemporal visual stimulus information does not need to be processed intentionally to influence perceived duration. Finally, the effect of nontemporal stimulus size on perceived duration was effectively modulated by the duration of the target intervals, suggesting a hitherto largely unrecognized role of temporal context for the effect of nontemporal stimulus size to become evident.

Larger visual stimuli are perceived to last longer from time to time: The internal clock is not affected by nontemporal visual stimulus size

Performance on interval timing is often explained by the assumption of an internal clock based on neural counting. According to this account, a neural pacemaker generates pulses, and the number of pulses relating to a physical time interval is recorded by a counter. Thus, the number of accumulated pulses is the internal representation of this interval. Several studies demonstrated that large visual stimuli are perceived to last longer than smaller ones presented for the same duration. The present study was designed to investigate whether nontemporal visual stimulus size directly affects the internal clock. For this purpose, a temporal reproduction task was applied. Sixty participants were randomly assigned to one of two experimental conditions with stimulus size being experimentally varied within either the target or the reproduction interval. A direct effect of nontemporal stimulus size on the pacemaker-counter system should become evident irrespective of whether stimulus size was experimentally varied within the target or the reproduction interval. An effect of nontemporal stimulus size on reproduced duration only occurred when stimulus size was varied during the target interval. This finding clearly argues against the notion that nontemporal visual stimulus size directly affects the internal clock. Furthermore, our findings ruled out a decisional bias as a possible cause of the observed differential effect of stimulus size on reproduced duration. Rather the effect of stimulus size appeared to originate from the memory stage of temporal information processing at which the timing signal from the pacemaker-counter component is encoded in reference memory.

Study protocol: young carers and young adult carers in Switzerland

BackgroundIn Switzerland, the issue of young carers and young adult carers - young people under the age of 18 and 24 respectively, who take on significant or substantial caring tasks and levels of responsibility that would usually be associated with an adult - has not been researched before. The number of these younger carers is unknown, as is the extent and kind of their caring activities and the outcomes for their health, well-being, psycho-social development, education, transitions to adulthood, future employability and economic participation.MethodsThe project is comprised of three stages:1.A national Swiss-wide online survey to examine awareness of the issue of younger carers amongst professional populations in the education, health and social services sectors;2.An online survey of 4800 Swiss pupils in schools using standardised instruments to identify the proportion and characteristics of pupils who are carers; and3.Semi-structured interviews with 20 families comprising family members with care needs and younger carers, to consolidate and validate the other stages of the study; and to hear directly from care-dependent family members and younger carers about their experiences of the issues identified in the surveys and in previous published research.DiscussionThe needs of younger carers and their ill and disabled family members in Switzerland have not been systematically investigated. This will be the first study in the country to investigate these issues and to develop evidence-based recommendations for policy and practice, drawing also on international research.The present study therefore fills an important national and international research gap. It will collect important data on the awareness, extent, kind and impact of caring amongst children and young people in Switzerland, and cross-link these findings with robust evidence from other countries. The study will reveal (a) the extent of awareness of the issue of young carers amongst medical, social, health, educational, and other groups in Switzerland; (b) the proportion and number of young carers amongst a normative child population, and what these young carers ‘do’ in terms of their caring roles; and (c) direct accounts by families of their care-giving and receiving experiences.