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Research Roundup

“Unit Bias” Determines the Acceptable Amount to Eat

According to Penn psychologists, hosts can do their dinner guests a big favor by serving smaller portions using smaller utensils.

The findings published in the journal Psychological Science, demonstrate the power of what the researchers have termed “unit bias”: the sense that a particular portion of food is appropriate.

“In terms of food, unit bias applies to what people think is the appropriate amount to consume, and it shows why smaller portion sizes can be just as satisfying,” said Andrew B. Geier, lead author and a graduate student in the department of psychology. “A 12-ounce can of soda and a 24-ounce bottle are both seen as single units. But be careful, the 24-ounce bottle, though viewed as one unit, is actually more than two and a half servings of soda.”

Unit bias can be seen in all types of consumption, whether it is how much food you take or how many times you ride the roller coaster. This bias, the researchers believe, is mostly derived from a culturally designated “proper” portion. It may also explain why portion size causes the French to eat much less than Americans.

According to Mr. Geier, people see food in natural consumption units, whether that is a single wrapped candy or a plateful of food.

Mr. Geier and Penn psychology professor Dr. Paul Rozin designed their experiments to observe how people choose to act in the presence of unlimited free food in public or private settings. In their study, they presented unsuspecting people with M&M’s candies, Tootsie Rolls and Philadelphia-style soft pretzels. When changing the size of the portions whether by offering a whole or half of a pretzel, for example people will see the offered portion as a single unit. In the pretzel experiment, people would take and eat an entire pretzel even though they were eating twice as much as the other people who were sufficiently satisfied with a half pretzel as a single unit.

They also observed how the means of serving the portion could influence how much food is eaten. In the M&M experiment, the researchers offered a large mixing bowl of the candy at the front desk of the concierge of an apartment building. Below the bowl hung a sign that read “Eat Your Fill” with “please use the spoon to serve yourself” written underneath.

If presented with a small spoon, most passersby would take a single scoop, even though the sign encouraged them to take more. If given a much larger spoon, the subjects would still take a single scoop, even though that one scoop contained much more candy. The subjects were inadvertently eating twice as much candy when the larger scoop happened to be in the bowl.

The researchers believe a better understanding of unit bias will aid in studying the psychology of obesity.

One-of-a-Kind Research Tool Focuses on KIDS

Children at risk who attend Head Start and other formal, center-based programs carry benefits of early care experiences at least through the second grade, according to new research from the Graduate School of Education.

This study, which looked at an entire group of children entering kindergarten in the school district of Philadelphia, was based on information gathered from a unique resource called KIDS (Kids Integrated Database System)—a data system that links individual administrative records of children and youth from each of the separate datasets maintained by city agencies. City leadership and Penn faculty have developed substantial agreements designed to protect the confidentiality of children and youth in KIDS, while providing a system for population-based evaluation to inform public services. When KIDS  opened for business last year, it made Philadelphia the only city in the country that could provide this kind of comprehensive information on the health, education and welfare of the city’s children and youth.

Children in the kindergarten group faced many risk factors prior to school entry such as poverty, birth and health risks and other factors (homelessness, maltreatment and placement outside the home), at significantly greater rates than national averages. But those who had formal preschool experiences were less likely to be in the lowest groups on national reading, writing, mathematics, and science achievement tests at the end of second grade. They were also less likely to have poor attendance and behavior problems.

Dr. John Fantuzzo, Diana Rausnitz Riklis Professor of Education and lead researcher on the study, explains, “The KIDS database is an extraordinarily powerful tool that makes visible the risks that threaten the well-being of urban children and youth and protective factors that promote well-being.” With it, Penn researchers were able to conduct the current study, which provides compelling evidence of the value of early childhood care and education programs.

New Technique for Better Diagnosis & Treatment of Stress

Using a different application of an fMRI (functional magnetic resonance imaging) technique, researchers at the School of Medicine have, for the first time, visualized the effects of everyday psychological stress in a healthy human brain. Their work, performed at Penn’s Center for Functional Neuroimaging, provides a neuroimaging marker of psychological stress–which will pave the way for the development of improved strategies for preventing or correcting the long-term health consequences of chronic stress. The researchers’ study appears in the November 21 online edition of Proceedings of the National Academy of Sciences.

In the Penn study, researchers induced stress on healthy subjects by asking them to quickly tackle challenging mental exercises while being monitored for performance. During the fMRI scans, the researchers also recorded subjects’ emotional responses–such as stress, anxiety, and frustration–and measured the corresponding changes in stress hormone and heart rate. Many subjects described themselves as being “flustered, distracted, rushed and upset” by the stress task.

The results showed increased cerebral blood-flow during the “stress test” in the right anterior portion of the brain (prefrontal cortex)–an area long associated with anxiety and depression. More interestingly, the increased cerebral blood-flow persisted even when the testing was complete. These results suggest a strong link between psychological stress and negative emotions. On the other hand, the prefrontal cortex is also associated with the ability to perform executive functions—such as working memory and goal-oriented behavior—that permit humans to adapt to environmental challenges and threats. “The message from this study is that while stress may be useful in increasing focus, chronic stress could also be detrimental to mental health,” concludes Dr. Jiongjiong Wang, assistant professor of radiology and principal investigator of the study.

To date, most fMRI studies have indirectly measured changes in cerebral blood-flow and metabolism induced by neural activation, using a technique that is sensitive to the oxygenation levels in blood. “The fMRI technique employed in our study–arterial spin labeling—can measure cerebral flood-flow directly,” states Dr. John A. Detre, associate professor of neurology and radiology, and senior author of the study. “This technique is very similar to PET (positron emission tomography) scanning, except that it’s entirely non-invasive—without the need for injections or radioactivity. In this technique, water molecules in subjects’ own blood are ‘tagged’ by the magnet and used as the natural contrast agent to measure cerebral blood-flow.”

Voter Questions Not Answered By Local Election Boards

Penn’s Fels Institute of Government released two reports in December on the state of election administration in the U.S. that show a failure by local boards of election to answer voter questions on Election Day. 

The findings are detailed in the final reports on hotline data from the MYVOTE1 project, during the November 2004 U.S. presidential election and the 2005 elections in New Jersey, New York and Pennsylvania.

The national hotline, 1.866.MYVOTE1, is a partnership between the Fels Institute and InfoVoter Technologies Corporation. 

The 2004 national hotline, the first of its kind in the country, took in 208,524 calls, processed more than 102,200 poll-location requests, transferred more than 96,000 calls to local election officials and recorded more than 56,000 complaints across all 50 states during the November 2004 elections.

The conclusions of the final reports on hotline data are that local boards of election do not answer their phones. In 2004, nationwide, 47% of calls transferred to local election board voter hotlines went unanswered. In 2005, despite a 97% drop off in call traffic, local county boards’ phone systems failed to answer in-bound calls 30% of the time.

In 2004, 51% of the hotline callers simply needed to find their polling places. In 2005,  the percentage of callers increased to 61%.

In 2004, nationwide, 55% of the 56,024 complaints recorded concerned registration or absentee-ballot systems. This number slightly increased in  2005 to 56% of the non-poll-location call traffic.

According to Christopher Patusky, executive director of the Fels Institute, the MyVote1 data shows that passage of the Help America Vote Act may have solved the wrong problem.  “Congress distributed $3 billion to states, primarily for new voting machines, and they missed a far more pervasive and insidious problem: local governments are not making basic electoral information about poll location and registration easily available to the public, and this is likely disenfranchising millions of voters,” he said.   

Most municipalities and counties post their polling locations based on precinct numbers.  Since most people don’t know their precinct numbers, they cannot learn their poll locations without calling local government help lines, and the MyVote1 data shows that many of these help lines are not reachable.

The full Fels Institute reports can be found at www.fels.upenn.edu.


  Almanac, Vol. 52, No. 17, January 10, 2006


January 10, 2006
Volume 52 Number 17


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