Idiom comprehension deficits in relation to corpus callosum agenesis and hypoplasia in children with spina bifida meningomyelocele

Idioms are phrases with figurative meanings that are not directly derived from the literal meanings of the words in the phrase. Idiom comprehension varies with: literality, whether the idiom is literally plausible; compositionality, whether individual words contribute to a figurative meaning; and contextual bias. We studied idiom comprehension in children with spina bifida meningomyelocele (SBM), a neurodevelopmental disorder associated with problems in discourse comprehension and agenesis and hypoplasia of the corpus callosum. Compared to age peers, children with SBM understood decomposable idioms (which are processed more like literal language) but not non-decomposable idioms (which require contextual analyses for acquisition). The impairment in non-decomposable idioms was related to congenital agenesis of the corpus callosum, which suggests that the consequences of impaired interhemispheric communication, whether congenital or acquired in adulthood, are borne more by configurational than by compositional language.     

A new method for calibrating perceptual salience across dimensions in infants: the case of color vs. luminance

We report a new method for calibrating differences in perceptual salience across feature dimensions, in infants. The problem of inter-dimensional salience arises in many areas of infant studies, but a general method for addressing the problem has not previously been described. Our method is based on a preferential looking paradigm, adapted to determine the relative salience of two stimuli. We report here on the case of stimuli differing in color and luminance, though the method has wider potential. We were able to determine on a psychophysical curve the point at which a color contrast was equally salient to infants as a given luminance contrast. We then used these calibrated, 'iso-salient' stimuli in an object memory study. Results showed that 6.5-month-old infants noticed a color, but not a luminance, change while tracking an occluded object. Our method should have numerous applications in the study of bottom-up effects on infant attention and visual working memory.     

A comparison of human performance in figural and navigational versions of the traveling salesman problem

Performance on a typical pen-and-paper (figural) version of the Traveling Salesman Problem was compared to performance on a room-sized navigational version of the same task. Nine configurations were designed to examine the use of the nearest-neighbor (NN), cluster approach, and convex-hull strategies. Performance decreased with an increasing number of nodes internal to the hull, and improved when the NN strategy produced the optimal path. There was no overall difference in performance between figural and navigational task modalities. However, there was an interaction between modality and configuration, with evidence that participants relied more heavily on the NN strategy in the figural condition. Our results suggest that participants employed similar, but not identical, strategies when solving figural and navigational versions of the problem. Surprisingly, there was no evidence that participants favored global strategies in the figural version and local strategies in the navigational version.     

Toddlers with Autism Spectrum Disorder are more successful at visual search than typically developing toddlers

Plaisted, O'Riordan and colleagues (Plaisted, O'Riordan & Baron-Cohen, 1998; O'Riordan, 2004) showed that school-age children and adults with Autism Spectrum Disorder (ASD) are faster at finding targets in certain types of visual search tasks than typical controls. Currently though, there is very little known about the visual search skills of very young children (1-3-year-olds) - either typically developing or with ASD. We used an eye-tracker to measure looking behavior, providing fine-grained measures of visual search in 2.5-year-old toddlers with and without ASD (this representing the age by which many children may first receive a diagnosis of ASD). Importantly, our paradigm required no verbal instructions or feedback, making the task appropriate for toddlers who are pre- or nonverbal. We found that toddlers with ASD were more successful at finding the target than typically developing, age-matched controls. Further, our paradigm allowed us to estimate the number of items scrutinized per trial, revealing that for large set size conjunctive search, toddlers with ASD scrutinized as many as twice the number of items as typically developing toddlers, in the same amount of time.     

When is motion 'motion'?

Examples of visual motion have become more and more abstract over the years, leading up to 'third-order' stimuli where direction is actually determined by the observer through top - down attention. But how far can this be pushed--are there motion stimuli that are yet more arbitrary and abstract? Actually, there is a broad class of 'conceptual motion' stimuli--things like a moving grating of faces, or a shifting pattern of words--that are perfect analogs to traditional 'perceptual motion' stimuli, solvable by the same motion computation and for which observers can readily make direction-of-motion judgments. Interestingly though, these do not produce a sensation of motion (among other automatic consequences of motion detection). Here we compare a luminance-based perceptual motion stimulus to a semantic-based conceptual motion stimulus to contrast the psychophysical hallmarks of these motion categories.     

Backward blocking in honeybees

Three experiments with foraging honeybees were designed to study the effect of experience with A on responding to B after AB+ training. In the first experiment, responding to B was the same whether the AB+ training was preceded or followed by A+ training. In the second experiment, responding to B after AB+ training was less in animals that also had A+ training than in control animals that were equally often reinforced in the absence of A; whether the A+ training preceded, was concurrent with, or followed the AB+ training made no difference. In the third experiment, responding to B after AB+ training was less when the AB+ training was followed by A+C- training than when it was followed by C+/A- training. These results, like those of some recent vertebrate experiments, take us beyond the traditional explanation of blocking in terms of impaired conditioning of B on AB+ trials and support the suggestion that the mechanism, still poorly understood, may nevertheless be a relatively simple one.     

Delayed Match Retrieval: a novel anticipation‐based visual working memory paradigm

We tested 8‐ and 10‐month‐old infants’ visual working memory (VWM) for object‐location bindings – what is where – with a novel paradigm, Delayed Match Retrieval, that measured infants’ anticipatory gaze responses (using a Tobii T120 eye tracker). In an inversion of Delayed‐Match‐to‐Sample tasks and with inspiration from the game Memory, in test trials, three face‐down virtual ‘cards’ were presented. Two flipped over sequentially (revealing, e.g. a swirl pattern and then a star), and then flipped back face‐down. Next, the third card was flipped to reveal a match (e.g. a star) to one of the previously seen, now face‐down cards. If infants looked to the location where the (now face‐down) matching card had been shown, this was coded as a correct response. To encourage anticipatory looks, infants subsequently received a reward (a brief, engaging animation) presented at that location. Ten‐month‐old infants performed significantly above chance, showing that their VWM could hold object‐location information for the two cards. Overall, 8‐month‐olds’ performance was at chance, but they showed a robust learning trend. These results corroborate previous findings (Kaldy & Leslie, 2005; Oakes, Ross‐Sheehy & Luck, 2006) and point to rapid development of VWM for object‐location bindings. However, compared to previous paradigms that measure passive gaze responses to novelty, this paradigm presents a more challenging, ecologically relevant test of VWM, as it measures the ability to make online predictions and actively localize objects based on VWM. In addition, this paradigm can be readily scaled up to test toddlers or older children without significant modification.