New insights into infant word learning


Summary: Early language acquisition may be related to memory representations that build over time rather than repeated connection between objects and words.

Source: Indiana University

Much is unknown about how infants begin to relate nouns to objects, a skill essential for later language development. A new study by researchers at Indiana University offers new insight into how infants reach this important milestone in human development.

The book, recently published in the Proceedings of the National Academy of Sciencesis led by Linda Smith, professor emeritus in the Department of Psychological and Brain Sciences in the College of Arts and Sciences at IU Bloomington, and Elizabeth Clerkin, postdoctoral researcher in the department.

Before they can speak, babies aged 7 to 11 months begin to associate the words they hear with everyday objects around them. To explain this phenomenon, the field of developmental psychology has focused on “naming moments”, when names and objects are presented to the infant at the same time.

However, object names are rarely spoken in tandem with objects, and the brain’s hippocampal memory system, which can form strong memories from singular events, may not be mature enough in infants for them to form lasting memories of these rare co-occurrences between objects and names.

“Our study shows that a different perspective is potentially needed to explain how infants make these connections by looking at time outside of naming moments,” Clerkin said. “We are focused on understanding how infants develop their memories for objects and categories more generally.”

In other words, early language learning may be related to memory representations that accumulate over time, rather than repeated connections between words and objects.

To conduct their study, Smith and Clerkin looked at infants’ everyday encounters with objects in their environment, during which infants gain “a deep and robust familiarity” with their surroundings.

The researchers compiled a catalog of objects and the heard names of objects as they occurred in infants’ daily lives. They then examined how these experiences align with infant memory systems in a way that would link objects and names to these rare moments of co-occurrence.

Specifically, the researchers relied on 67 hours of audiovisual recordings of the meals of 14 infants, aged 7 to 11 months, sampling the statistical regularities of infants’ daily interactions with people and objects.

This data is part of a much larger dataset called the Home View Project, for which Smith’s lab fitted infants with front-facing cameras so parents or caregivers could record several hours of daily activity in their home.

“When scientists think about how well infants learn words, they traditionally focus on internal cognitive mechanisms,” Smith said.

This composite image shows a series of images from the perspective of an eight-month-old child. This is an example of the data used in the study. Credit: Department of Psychological and Brain Sciences

“This assumption about nouns and objects co-occurring is not wrong, but if you look at infants’ learning environment more broadly, you see their task of learning – and the mechanisms by which that learning can occur. – differently. We need to study the structure of these learning environments, not just the internal cognitive mechanism, because this will tell us more about what needs to be in place for children to learn language.

A full understanding of the learning environment could allow researchers and clinicians to develop interventions for children considered “late speakers”, revealing ways to improve the environment to help children who learn language longer. slowly than their peers.

This broader view of learning object names ultimately aligns with a memory system operating in the neocortex of the brain that is known to be functional in early childhood and constructs memory representations over long periods of time, Smith said.

She added that when well-established memories are reactivated by new information, the new information is quickly integrated into the existing memory. A single instance of hearing the word “table”, for example, will make sense when heard in the context of visual memories of a table.

It is through these two “time scales of experience” – and the workings of the neocortical memory system – that researchers say infants make their first connections between words and objects.

“The idea is that over long periods of time, memory traces for visual objects slowly accumulate in the neocortex,” Clerkin said. “When a word is spoken at a specific time and the memory trace is also reactivated near the name, this mechanism allows infants to establish a connection quickly.”

The researchers said their work also has important implications for machine learning researchers designing and building artificial intelligence to recognize categories of objects. This work, which focuses on how nouns teach categories, requires massive training for machine learning systems to even come close to recognizing human objects.

The involvement of the infant’s journey in this study suggests a novel approach to machine learning, in which training is structured more like the natural environment, and object categories are first learned without labels, after which they are are linked to tags.

About this language and learning research news

Author: Press office
Source: Indiana University
Contact: Press Office – Indiana University
Image: Image is in public domain

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Original research: Free access.
“Real-world statistics at two time scales and the mechanism of infants’ learning of object names” by Elizabeth M. Clerkin et al. PNAS


Real-world statistics at two time scales and the mechanism for children to learn object names

Babies start learning the visual referents of names before their first birthday.

Despite considerable empirical and theoretical efforts, little is known about the statistics of experiments that allow infants to break into learning object names.

We used wearable sensors to collect babies’ experiences of visual objects and their heard names for 40 early-learned categories.

The data analyzed came from a context that occurs several times a day and includes objects with names learned early: mealtime. The statistics reveal two distinct time scales of experience.

On the time scale of many meal episodes (not = 87), visual categories were ubiquitous, but the naming of objects within each of these categories was very rare.

On the timescale of single meal episodes, nouns and referents coexist, but each noun-referent pair appears in very few meal episodes.

The statistics are consistent with the gradual learning of visual categories across many episodes and the rapid learning of name-object mappings within individual episodes.

Both timescales are also consistent with a known cortical learning mechanism for learning one-episode associations: new information, the name heard, is incorporated into well-established memories, the category of objects seen, when the new information coincides with the reactivation of this name. slowly established memory.


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