Neuroscience
Normally we have a slight bias to the left-hand side of space. So if we’re asked to mark the centre of a line, for example, we tend to overestimate the length of the left-hand portion. Now Tom Manly (pictured) at the MRC Cognition and Brain Sciences Unit in Cambridge and colleagues have shown that as we grow tired this bias is shifted over to the right-hand side. The finding could have implications for the treatment uni-lateral spatial neglect – an inability to attend to things on one side of space that often affects people after they’ve had a stroke.
Manly’s team tested 10 healthy volunteers who worked shifts at Addenbrooke’s Hospital. They were presented with horizontal lines with a vertical divider and were asked to say which half of the line was longer. When they’d just come on shift they showed the usual bias of overestimating the left-hand portion, but at the end of a shift they showed the opposite bias. In a second study, six volunteers from the authors’ own MRC research unit performed a similar task for 60 minutes. As the task wore on, their spatial bias shifted from the left to the right. The findings complement previous work showing uni-lateral neglect following stroke can be worse when patients are tired.
“Our findings suggest that the dramatic effects on conscious awareness resulting from damage to [fronto-parietal] networks in patients and the subsequent modulation [of their neglect] with changes in alertness, may be echoed in a much milder form in healthy participants”, the authors said.
_________________________________
Manly, T. Dobler, V.B., Dodds, C.M. & George, M.A. (2005). Rightward shift in spatial awareness with declining alertness. Neuropsychologia, 43, 1721-1728.
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
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Neuroscience
Hemispheric bias shifts with tiredness
Normally we have a slight bias to the left-hand side of space. So if we’re asked to mark the centre of a line, for example, we tend to overestimate the length of the left-hand portion. Now Tom Manly (pictured) at the MRC Cognition and Brain Sciences Unit in Cambridge and colleagues have shown that as we grow tired this bias is shifted over to the right-hand side. The finding could have implications for the treatment uni-lateral spatial neglect – an inability to attend to things on one side of space that often affects people after they’ve had a stroke.Manly’s team tested 10 healthy volunteers who worked shifts at Addenbrooke’s Hospital. They were presented with horizontal lines with a vertical divider and were asked to say which half of the line was longer. When they’d just come on shift they showed the usual bias of overestimating the left-hand portion, but at the end of a shift they showed the opposite bias. In a second study, six volunteers from the authors’ own MRC research unit performed a similar task for 60 minutes. As the task wore on, their spatial bias shifted from the left to the right. The findings complement previous work showing uni-lateral neglect following stroke can be worse when patients are tired.
“Our findings suggest that the dramatic effects on conscious awareness resulting from damage to [fronto-parietal] networks in patients and the subsequent modulation [of their neglect] with changes in alertness, may be echoed in a much milder form in healthy participants”, the authors said.
_________________________________
Manly, T. Dobler, V.B., Dodds, C.M. & George, M.A. (2005). Rightward shift in spatial awareness with declining alertness. Neuropsychologia, 43, 1721-1728.
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
- Novelty Seekers Are Biased To The Right
Most people show a slight bias to the left-hand side of space. In other words, presented with a horizontal line and asked to identify its midway point, most of us will mark a position slightly too far to the left. Increasingly, however, research is showing...
- Satisfaction Guaranteed!
Our bias for the left-hand side of space could be distorting large-scale surveys. Past research has shown that when people are asked to bisect a horizontal line down the centre, most will cross the line too far to the left. This leftward bias is thought...
- The 'power Of One' - Why Larger Portions Cause Us To Eat More
The effect of portion size on how much people eat is something of a mystery – why don’t they simply leave what they don’t want, or alternatively, where possible, why not help themselves to more? Andrew Geier and colleagues at the University of Pennsylvania...
- Forget Stroop, Here's The Snarc
You’ve probably heard of the Stroop effect (if not, see here), now let me introduce you to the SNARC. The Spatial Numerical Association of Response Codes (SNARC) effect is the observation that people are faster to make a judgment about a number if the...
- Detecting Psychological Distress From Where A Patient Sits
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