First a "leaked" study in press in Perspectives on Psychological Science confirmed suspicion focused on the use of inappropriately adjusted correlations in many studies using fMRI. Edward Vul and colleagues surveyed 54 articles that do not contain sufficient information in the method section to confirm how the analyses were produced and find over half of the studies to contain "grossly" inflated correlations.
The damning conclusion was that "a disturbingly large, and quite prominent, segment of social neuroscience research is using seriously defective research methods and producing a profusion of numbers that should not be believed."
The article is freely available here: Voodoo Correlations in Social Neuroscience
The week in neuroscience then went from voodoo correlations based on questionable research methodology to a questioning of the very foundations of the core technique of neuroscience: functional brain imaging. Blood flow changes picked up by fMRI scanners may not reflect the metabolic demand produced by local neural activity is the message that comes across strongly in a letter to Nature by Yevgeniy B. Sirotin and colleagues this week. The authors monitored neural activity and blood flow in two monkeys (they only need one intact one to show fMRI inaccuracies) whilst performing visual tasks. The key finding was that between stimuli there was virtually no neural activity but increased blood flow was observed suggesting that anticipation of expected tasks rather than neural activity may be a driving force behind blood flow changes.
Commentry: Another shock for brain imaging research
Friday, January 30, 2009
Exposure to innocent victims increases discounting
A study by Mitchell Callan and colleagues from the latest issue of the Journal of Experimental Social Psychology shows that watching a video depicting the suffering of an innocent vs. a non-innocent victim increased discounting across six time delays. The authors reasoned that forming a "personal contract" to take a larger sum at a later date rather than a smaller sum now may be perceived as a bad idea in an unjust world where investments may not pay off.
Looking through the lens of the recession, rife with innocent victims, you wonder to what extent economic instability leads to more impulsive choices. When Ryanair's CEO Michael O'Leary swept in to secure huge discounts on Boeing 737-800's in the wake of 9/11, he was clearly capitalising on what he had the vision to recognise would be a passing scare. Though the current crisis appears far from transient it would be worth documenting its effects on economic decision-making. Loss-aversion may increase and though people are certainly saving money in the event of a shock, trade-off's should increase between wanting access to money now vs more money at a fixed time far into the future.
Looking through the lens of the recession, rife with innocent victims, you wonder to what extent economic instability leads to more impulsive choices. When Ryanair's CEO Michael O'Leary swept in to secure huge discounts on Boeing 737-800's in the wake of 9/11, he was clearly capitalising on what he had the vision to recognise would be a passing scare. Though the current crisis appears far from transient it would be worth documenting its effects on economic decision-making. Loss-aversion may increase and though people are certainly saving money in the event of a shock, trade-off's should increase between wanting access to money now vs more money at a fixed time far into the future.
Private Sector Data on the Labour Market
Alan Krueger describes here (on the Economix Blog) how the Gallup Organisation has developed five new indicators of daily economic activity. Every day Gallup polls 1,000 people; and in relation to the job market, it asks the following to those who work:
“Now thinking more generally about the company or business you work for, including all of its employees. Based on what you know or have seen, would you say that, in general, your company or employer is — 1) hiring new people and expanding the size of its workforce, 2) not changing the size of its work force, or 3) letting people go and reducing the size of its work force?”
Krueger reports that the gap between hiring and letting people go is strongly correlated with the number of new unemployment insurance claims each week. The Gallup data have the advantage of being computed daily, and so they provide an early warning of where the labor market is heading.
“Now thinking more generally about the company or business you work for, including all of its employees. Based on what you know or have seen, would you say that, in general, your company or employer is — 1) hiring new people and expanding the size of its workforce, 2) not changing the size of its work force, or 3) letting people go and reducing the size of its work force?”
Krueger reports that the gap between hiring and letting people go is strongly correlated with the number of new unemployment insurance claims each week. The Gallup data have the advantage of being computed daily, and so they provide an early warning of where the labor market is heading.
Estimating the Public-Private Wage Gap in Russia
A new IZA working paper by Gimpelson and Lukiyanova discusses the institutional framework for public sector wage setting in Russia. They apply the switching regression technique that allows correcting for non-random sector selection, and find that there is significant cross-group variation in the wage gap. The paper concludes that wages in the public sector should be linked to private sector wages at the regional level.
Thursday, January 29, 2009
Do Cognitive Skills Depend on Non-Cognitive Skills? And If So, What Does the Labour Market Reward?
In a previous post, I mentioned research on behavioural determinents of earnings by Bowles et al. (2001); these authors report that cognitive skills represent less than a fifth of the return to schooling. They suggest that the remaining 82% of the return to schooling could either be associated with more advanced cognitive skills that are not captured by basic measures, or with noncognitive skills. More recently, Pasche (2008) finds that over half the return to schooling is constituted of basic cognitive skills. Either way, the bias of non-cognitive personality traits is important when estimating the returns to education.
Research by Borghans, Meijers and ter Weel (reported at the AEA meeting earlier this month), examines the role of noncognitive skills in explaining cognitive test scores. They measure noncognitive skills both by personality traits and economic preference parameters; and the idea is that noncognitive skills might affect the effort people put into a test to obtain good results.
The authors experimentally varied the rewards for questions in a cognitive test to measure to what extent people are sensitive to financial incentives. To distinguish increased mental effort from extra time investments, they also varied the questions’ time constraints. Favourable personality traits such as high performance-motivation and an internal locus of control are associated with high test scores in the absence of rewards; which the authors say is consistent wiith trying as hard as possible.
In contrast, favourable economic preference parameters (low discount rate, low risk aversion) are associated with increases in time investments when incentives are introduced, consistent with a rational economic model in which people only invest when there are monetary returns.
The main conclusion of the research is that individual behavior in cognitive tests depends on noncognitive skills. This means that de-compositions of the returns to schooling may be biased towards cognitive skills in ways that have not been considered before. This underscores further the need to consider the bias of non-cognitive personality traits when estimating the returns to education.
Research by Borghans, Meijers and ter Weel (reported at the AEA meeting earlier this month), examines the role of noncognitive skills in explaining cognitive test scores. They measure noncognitive skills both by personality traits and economic preference parameters; and the idea is that noncognitive skills might affect the effort people put into a test to obtain good results.
The authors experimentally varied the rewards for questions in a cognitive test to measure to what extent people are sensitive to financial incentives. To distinguish increased mental effort from extra time investments, they also varied the questions’ time constraints. Favourable personality traits such as high performance-motivation and an internal locus of control are associated with high test scores in the absence of rewards; which the authors say is consistent wiith trying as hard as possible.
In contrast, favourable economic preference parameters (low discount rate, low risk aversion) are associated with increases in time investments when incentives are introduced, consistent with a rational economic model in which people only invest when there are monetary returns.
The main conclusion of the research is that individual behavior in cognitive tests depends on noncognitive skills. This means that de-compositions of the returns to schooling may be biased towards cognitive skills in ways that have not been considered before. This underscores further the need to consider the bias of non-cognitive personality traits when estimating the returns to education.
Extraversion and Expectations about the Returns to Higher Education
Gergely and Kézdi discuss college enrollment, the Big Five personality traits (in particular extraversion), and earnings expectations in the context of Hungarian higher education. They report that conditional on IQ and various measures of other personality traits, as well as past schooling experience and past behavioral problems, more extraverted men expect lower returns to higher education.
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