Can monkeys choose optimally when faced with noisy stimuli and unequal rewards?

February 12, 2009

Even when faced with distractions, monkeys are able to consistently choose the path of greatest reward, according to a study conducted by researchers from Princeton and Stanford Universities. The study, published February 13th in the open-access journal PLoS Computational Biology, adds to the growing evidence that animal foraging behavior can approach optimality, and could provide a basis for understanding the computations involved in this and related tasks.

In the article, Feng and colleagues address ongoing experiments relating to monkeys' abilities to distinguish among moving stimuli. Monkeys were trained to identify the direction of motion of a field of randomly-moving dots, a fraction of which move coherently in one of two possible directions. But unlike most previous studies in which all correct choices were equally rewarded, different sized rewards were now associated with different stimuli, and the researchers developed a mathematical model to predict how the animals should balance sensory information and prior expectations regarding rewards, in order to maximize their net returns. The study is unique in that it assesses not only the accuracy of decisions, but also the overall harvesting efficiency.

Remarkably, the monkeys devised a near-optimal strategy. Across the course of several hundred choices in each daily session, with randomly interspersed coherence and reward conditions, their typical harvesting efficiency fell within 1-2% of the theoretical maximum. These findings reveal impressive decision-making ability, and raise important questions about the neural mechanisms that underlie it.
-end-
PLEASE ADD THIS LINK TO THE PUBLISHED ARTICLE IN ONLINE VERSIONS OF YOUR REPORT: http://dx.plos.org/10.1371/journal.pcbi.1000284 (link will go live upon embargo lift)

CITATION: Feng S, Holmes P, Rorie A, Newsome WT (2009) Can Monkeys Choose Optimally When Faced with Noisy Stimuli and Unequal Rewards? PLoS Comput Biol 5(2): e1000284. doi:10.1371/journal.pcbi.1000284

CONTACT:

Dr. Phil Holmes
pholmes@Math.Princeton.edu

Disclaimer

This press release refers to an upcoming article in PLoS Computational Biology. The release is provided by journal staff and the article authors. Any opinions expressed in this release or article are the personal views of the journal staff and/or article contributors, and do not necessarily represent the views or policies of PLoS. PLoS expressly disclaims any and all warranties and liability in connection with the information found in the releases and articles and your use of such information.

About PLoS Computational Biology

PLoS Computational Biology (www.ploscompbiol.org) features works of exceptional significance that further our understanding of living systems at all scales through the application of computational methods. All works published in PLoS Computational Biology are open access. Everything is immediately available subject only to the condition that the original authorship and source are properly attributed. Copyright is retained by the authors. The Public Library of Science uses the Creative Commons Attribution License.

About the Public Library of Science

The Public Library of Science (PLoS) is a non-profit organization of scientists and physicians committed to making the world's scientific and medical literature a freely available public resource. For more information, visit http://www.plos.org.

PLOS

Related Monkeys Articles from Brightsurf:

Monkeys appreciate lifelike animation
Monkeys can overcome their aversion to animated monkeys through a more realistic avatar, according to research recently published in eNeuro.

Why monkeys choose to drink alone
Why do some people almost always drop $10 in the Salvation Army bucket and others routinely walk by?

Marmoset monkeys can learn a new dialect
Monkeys and other animals communicate through calls that can differ depending on region.

Monkeys can also thank their body for vocal development, not only their brain
Development of vocal behavior during maturation is typically attributed to the brain.

Monkeys like alcohol at low concentrations, but probably not due to the calories
Fruit-eating monkeys show a preference for concentrations of alcohol found in fermenting fruit, but do not seem to use alcohol as a source of supplementary calories, according to a study by researchers from Linköping University, Sweden, and the Universidad Veracruzana, Mexico.

Flies may also spread disease among monkeys and apes
People the world over have a good sense that we do not want flies landing on our food.

Boosting glutamate reduces anxiety in monkeys
Researchers studying male and female marmosets have homed in on the primate brain circuitry responsible for individual differences in overall anxiety.

Marmoset monkeys expect the melody's closing tone
In speech and music, words and notes depend on each other.

What social stress in monkeys can tell us about human health
A new University of Washington-led study examines one key stress-inducing circumstance -- the effects of social hierarchy -- and how cells respond to the hormones that are released in response to that stress.

Monkeys do not start to resemble their parents before puberty
Researchers from the Max Planck Institute for Evolutionary Anthropology and the University of Leipzig presented experienced human raters with digital images of rhesus macaques of different ages and asked them to identify related individuals.

Read More: Monkeys News and Monkeys Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.