Frontiers in Psychology

Inherently analog quantity representations in olive baboons (Papio anubis)

Human babies can 'count' up to 3 or 4, but for greater numbers, infants - and adults when distracted from counting precisely - use the analog system for comparing between counts of objects. Through this system, the relative difference between two counts is more important than the absolute difference, making it easier to distinguish 20 from 10 than 30 from 20. Previous studies suggested that monkeys also use the analog system, but this has remained controversial.

In this study Jessica Cantlon and colleagues from the University of Rochester tested for the capacity of eight olive baboons from Seneca Park Zoo to compare between the numbers 1 to 8. Importantly, these baboons had never been used in any psychological tests, suggesting that the results are representative of wild-living baboons. The baboons were more likely to choose the greater number of peanuts if the relative difference between two counts was larger, irrespective of the absolute difference. The authors conclude that the analog system is probably the ancestral mechanism for comparing quantities in primates, while the ability to count might be an evolutionarily recent trait unique to humans.

URL: http://www.frontiersin.org/Comparative_Psychology/10.3389/fpsyg.2013.00253/abstract

Frontiers in Neuroscience

Common muscle synergies for balance and walking

Researchers from Georgia Tech and Emory University have improved understanding of the neural control of multiple muscles that must be coordinated in activities such as walking and maintaining balance. Lena Ting and colleagues show that muscle synergies, or patterns of muscles recruited by a single neural command, may be a fundamental building block for constructing movement.

The new concept of muscle synergy represents a fundamental shift in the understanding of movement control and the findings have strong implications for addressing motor impairments and rehabilitation, because it has potential to specifically reveal neural mechanisms underlying motor deficit and recovery.

Muscle synergies are like building blocks for movement, providing a library of possible actions available to an individual. Like musical chords, each muscle synergy specifies how particular muscles (or notes) are concurrently activated in a functional unit. Just as one note may belong to several different chords, each muscle can belong to more than one muscle synergy. Through combinations of muscle synergies, a wide repertoire of movements becomes possible. Using computational methods, Ting and colleagues helped to reveal this underlying structure in muscle activity, which is not always evident in movements where many muscle synergies are simultaneously used.

URL: http://www.frontiersin.org/computational_neuroscience/10.3389/fncom.2013.00048/abstract

Frontiers in Psychiatry

What Italian defense attorneys know about factors affecting eyewitness accuracy

Surveys of the beliefs and knowledge of legal professionals about factors that affect eyewitness accuracy suggest that judges and police officers are no more knowledgeable about eyewitness testimony than are jurors or the general public. A majority, or a substantial minority, of the legal professionals surveyed in the US, Norway, Estonia, China and Sweden harbor ideas about eyewitness memory that are not supported by available research, which suggests that many court decisions may be based on folklore with little support in memory science. The only exception to this pattern was the US defense attorneys, who knew more about eyewitness memory than the other legal professionals and performed closer to eyewitness experts. In this paper, Giuseppe Sartori surveyed Italian defense attorneys, and the results more or less confirmed the results from the US survey: Defense attorneys are more aware of the pitfalls of eyewitness memory than are other legal professionals. The role of defense attorneys in legal proceedings may alert them to the pitfalls of the eyewitness memory and make them more skeptical of it.

URL: http://www.frontiersin.org/Forensic_Psychiatry/10.3389/fpsyt.2013.00028/abstract

Also of interest, published last week in Frontiers in Neuroscience:

Motor development and motor resonance difficulties in autism: relevance to early intervention for language and communication skills

Professionals have long attempted to support the development of language in Autistic children but with mixed outcomes. While not all of the current interventions used are effective, a new paper authored by researchers from the University of Birmingham, says there is hope for progress by using interventions based on understanding natural language development and the role of motor and "motor mirroring" behaviour in toddlers.

URL: http://www.frontiersin.org/Integrative_Neuroscience/10.3389/fnint.2013.00030/abstract