Infants’ Recognition of Speech More Sophisticated Than Previously Known

ScienceDaily (July 17, 2012) — The ability of infants to recognize speech is more sophisticated than previously known, researchers in New York University’s Department of Psychology have found. Their study, which appears in the journal Developmental Psychology, showed that infants, as early as nine months old, could make distinctions between speech and non-speech sounds in both humans and animals.


“Our results show that infant speech perception is resilient and flexible,” explained Athena Vouloumanos, an assistant professor at NYU and the study’s lead author. “This means that our recognition of speech is more refined at an earlier age than we’d thought.”

It is well-known that adults’ speech perception is fine-tuned — they can detect speech among a range of ambiguous sounds. But much less is known about the capability of infants to make similar assessments. Understanding when these abilities become instilled would shed new light on how early in life we develop the ability to recognize speech.

In order to gauge the aptitude to perceive speech at any early age, the researchers examined the responses of infants, approximately nine months in age, to recorded human and parrot speech and non-speech sounds. Human (an adult female voice) and parrot speech sounds included the words “truck,” “treat,” “dinner,” and “two.” The adult non-speech sounds were whistles and a clearing of the throat while the parrot non-speech sounds were squawks and chirps. The recorded parrot speech sounds were those of Alex, an African Gray parrot that had the ability to talk and reason and whose behaviors were studied by psychology researcher Irene Pepperberg.

Since infants cannot verbally communicate their recognition of speech, the researchers employed a commonly used method to measure this process: looking longer at what they find either interesting or unusual. Under this method, looking longer at a visual paired with a sound may be interpreted as a reflection of recognition. In this study, sounds were paired with a series of visuals: a checkerboard-like image, adult female faces, and a cup.

The results showed that infants listened longer to human speech compared to human non-speech sounds regardless of the visual stimulus, revealing the ability recognize human speech independent of the context.

Their findings on non-human speech were more nuanced. When paired with human-face visuals or human artifacts like cups, the infants listened to parrot speech longer than they did non-speech, such that their preference for parrot speech was similar to their preference for human speech sounds. However, this did not occur in the presence of other visual stimuli. In other words, infants were able to distinguish animal speech from non-speech, but only in some contexts.

“Parrot speech is unlike human speech, so the results show infants have the ability to detect different types of speech, even if they need visual cues to assist in this process,” explained Vouloumanos.

The study’s other co-author was Hanna Gelfand, an undergraduate at NYU’s College of Arts and Science at the time of the study and currently a graduate student in the San Diego State University/University of California, San Diego Joint Doctoral Program in Language and Communicative Disorders.

 

Journal Reference:

  1. Athena Vouloumanos, Hanna M. Gelfand. Infant Perception of Atypical Speech Signals. Developmental Psychology, 2012; DOI: 10.1037/a0029055

 

New York University (2012, July 17). Infants’ recognition of speech more sophisticated than previously known. ScienceDaily. Retrieved July 18, 2012, from http://www.sciencedaily.com­ /releases/2012/07/120717100050.htm

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What We Know and Don’t Know About Earth’s Missing Biodiversity

ScienceDaily (July 17, 2012) — Most of the world’s species are still unknown to science although many researchers grappled to address the question of how many species there are on Earth over the recent decades. Estimates of non-microbial diversity on Earth provided by researchers range from 2 million to over 50 million species, with great uncertainties in numbers of insects, fungi, nematodes, and deep-sea organisms.


Some groups of species, such as plants and birds, are well-known, with scientists discovering relatively few new ones each year. For insects and fungi, however, it is almost impossible to guess how many unknown species there are.

These findings were revealed in a first-ever study by researchers from the National University of Singapore (NUS), James Cook University in Australia, Microsoft Research in the United Kingdom and Duke University in the United States, and was first published in Trends in Ecology & Evolution on 10 July 2012.

The researchers emphasise the importance of technology such as DNA barcoding, new databases and crowd-sourcing, that could greatly accelerate the rate of species discovery.

Unknown Biodiversity: Estimates

In their study, Scheffers and his colleagues collated information from numerous studies that attempt to estimate numbers and characteristics of unknown biodiversity. What may seem like straight forward questions about Earth’s biodiversity are “deceptively complex,” warned the researchers.

“What we do know,” said lead researcher Brett R. Scheffers, who is from the Department of Biological Sciences at NUS, “is that these unknown species are likely living in places where they are in danger of extinction, and that we could lose many before we realise how valuable they are.”

“The problem is how one protects an animal that has never been seen,” he added. “What we want to know is how many species there are, what they look like and where do they live.”

The report suggests that many of these species are important for medicine, water purification and provide numerous other services for humanity. For instance, a group of marine snails — the cone snail — is important for drug development ranging from pain killers to treatment of neurological diseases. Many species of these snails are newly discovered, and there is likely many more still waiting to be discovered.

“We simply cannot afford to lose these species because of neglect and short-sided economic gains,” explained co-author Professor William Laurance of James Cook University in Cairns, Australia.

Major Challenges

The researchers pointed out major challenges that complicate biodiversity inventory. These include accidentally assigning two different species the same name, and animals that look nearly identical and can therefore only be identified by genetic analyses.

Co-author Dr. Lucas Joppa from Microsoft Research in Cambridge, United Kingdom said, “Missing species will likely be hard to find, such as deep-sea organisms, high mountain species or those species that live beneath the ground. Missing biodiversity will be small — both in body size and the amount of area that they live in. This is a concern as both of these factors relate to a species vulnerability to environmental disturbances.”

Advances in Technology

Although these challenges present real struggles for future records, Scheffers and his colleagues stress that progress is being made. Novel techniques, such as DNA barcoding, new databases and crowd-sourcing, could greatly accelerate the rate of species discovery.

“New technologies such as environmental DNA analyses now exist and can detect a species’ presence from mere water samples without ever visually observing it,” said Scheffers. “Data sharing technologies over the Internet about species locations and discoveries are also expediting and expanding the catalogue of life.”

 

Journal Reference:

  1. Brett R. Scheffers, Lucas N. Joppa, Stuart L. Pimm, William F. Laurance. What we know and don’t know about Earth’s missing biodiversity. Trends in Ecology & Evolution, 2012; DOI: 10.1016/j.tree.2012.05.008

 

National University of Singapore (2012, July 17). What we know and don’t know about Earth’s missing biodiversity. ScienceDaily. Retrieved July 18, 2012, from http://www.sciencedaily.com­ /releases/2012/07/120717084802.htm