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Justin Halberda

Publications and source records attributed to Justin Halberda.

4 recordsLinked to original sources

Is this a dax which I see before me? Use of the logical argument disjunctive syllogism supports word-learning in children and adults.

Many authors have argued that word-learning constraints help guide a word-learner's hypotheses as to the meaning of a newly heard word. One such class of constraints derives from the observation that word-learners of all ages prefer to map novel labels to novel objects in situations of referential ambiguity. In this paper I use eye-tracking to document the mental computations that support this word-learning strategy. Adults and preschoolers saw images of known and novel objects, and were asked to find the referent of known and novel labels. Experiment 1 shows that adults systematically reject a known distractor (e.g. brush) before mapping a novel label (e.g. "dax") to a novel object. This is consistent with the proposal that participants worked through a Disjunctive Syllogism (i.e. Process-of-Elimination) to motivate the mapping of the novel label to the novel object. Experiment 2 shows that processing is similar for adults performing an implicit Disjunctive Syllogism (e.g. "the winner is the dax") and an explicit Disjunctive Syllogism (e.g. "the winner is not the iron"). Experiment 3 reveals that similar processes govern preschoolers' mapping of novel labels. Taken together, these results suggest that word-learners use Disjunctive Syllogism to motivate the mapping of novel labels to novel objects.

Adolescent↗

Multiple spatially overlapping sets can be enumerated in parallel.

A system for nonverbally representing the approximate number of items in visual and auditory arrays has been documented in multiple species, including humans. Although many aspects of this approximate number system are well characterized, fundamental questions remain unanswered: how does attention select which items in a scene to enumerate, and how many enumerations can be computed simultaneously? Here we show that when presented an array containing different numbers of spatially overlapping dots of many colors, human adults can select and enumerate items on the basis of shared color and can enumerate approximately three color subsets from a single glance. This three-set limit converges with previously observed three-item limits of parallel attention and visual short-term memory. This suggests that participants can select a subset of items from a complex array as a single individual set, which then serves as the input to the approximate number system.

Adult↗

Infants chunk object arrays into sets of individuals.

Research suggests that, using representations from object-based attention, infants can represent only 3 individuals at a time. For example, infants successfully represent 1, 2, or 3 hidden objects, but fail with 4 (Developmental Science 6 (2003) 568), and a similar limit is seen in adults' tracking of multiple objects (see Cognitive Psychology 38 (1999) 259). In the present experiments we used a manual search procedure to ask whether infants can overcome this limit of 3 by chunking individuals into sets. Experiments 1 and 2 replicate infants' failure to represent a total of 4 objects. We then show that infants can exceed this limit when items are spatiotemporally grouped into two sets of 2 prior to hiding, leading infants to successfully represent a total of 4 objects. Experiment 3 demonstrates that infants tracked the 4 objects as two sets of 2, searching for each set in its correct hiding location. That infants represented the number of individuals in each set is demonstrated by their reaching for the correct number of objects in each location. These results suggest that by binding individuals into sets, infants can increase their representational capacity. This is the first evidence for chunking abilities in infants.

Attention↗

The development of a word-learning strategy.

Two studies investigated young infants' use of the word-learning principle Mutual Exclusivity. In Experiment 1, a linear relationship between age and performance was discovered. Seventeen-month-old infants successfully used Mutual Exclusivity to map novel labels to novel objects in a preferential looking paradigm. That is, when presented a familiar and a novel object (e.g. car and phototube) and asked to "look at the dax", 17-month-olds increased looking to the novel object (i.e. phototube) above baseline preference. On these trials, 16-month-olds were at chance. And, 14-month-olds systematically increased looking to the familiar object (i.e. car) in response to hearing the novel label "dax". Experiment 2 established that this increase in looking to the car was due solely to hearing the novel label "dax". Several possible interpretations of the surprising form of failure at 14 months are discussed.

Fixation, Ocular↗