The early acquisition of verb meaning in German by normally developing and language impaired children

The research reported here focuses on the early acquisition of event structure in German. Based on longitudinal studies from 5 normally developing (ND) and 6 language-impaired (LI) children, a model of "event structural bootstrapping" is presented that spells out how ND children log into the verb lexicon. They project a target-consistent event tree, depicting the head-of-event of transitions. Young LI children, failing to employ this bootstrapping strategy, resort to radically underspecified event representations. The results from a truth-value judgment experiment with 16 ND and 16 LI children showed that ND children perform correctly on transitional verbs, while LI children perform at chance level on the same tasks. These findings are accounted for by the model of event structural bootstrapping to the extent that LI children lack an explicit representation of the head-of-event.     

Linguistically mediated visual search

During an individual's normal interaction with the environment and other humans, visual and linguistic signals often coincide and can be integrated very quickly. This has been clearly demonstrated in recent eyetracking studies showing that visual perception constrains on-line comprehension of spoken language. In a modified visual search task, we found the inverse, that real-time language comprehension can also constrain visual perception. In standard visual search tasks, the number of distractors in the display strongly affects search time for a target defined by a conjunction of features, but not for a target defined by a single feature. However, we found that when a conjunction target was identified by a spoken instruction presented concurrently with the visual display, the incremental processing of spoken language allowed the search process to proceed in a manner considerably less affected by the number of distractors. These results suggest that perceptual systems specialized for language and for vision interact more fluidly than previously thought.     

Mixed-model pairwise multiple comparisons of repeated measures means

One approach to the analysis of repeated measures data allows researchers to model the covariance structure of the data rather than presume a certain structure, as is the case with conventional univariate and multivariate test statistics. This mixed-model approach was evaluated for testing all possible pairwise differences among repeated measures marginal means in a Between-Subjects x Within-Subjects design. Specifically, the authors investigated Type I error and power rates for a number of simultaneous and stepwise multiple comparison procedures using SAS (1999) PROC MIXED in unbalanced designs when normality and covariance homogeneity assumptions did not hold. J. P. Shaffer's (1986) sequentially rejective step-down and Y. Hochberg's (1988) sequentially acceptive step-up Bonferroni procedures, based on an unstructured covariance structure, had superior Type I error control and power to detect true pairwise differences across the investigated conditions.     

Biased interpretation of evidence by mock jurors

Predecisional distortion is jurors' biased interpretation of new evidence to support whichever verdict is tentatively favored as a trial progresses. In 2 experiments, students and prospective jurors distorted evidence from a mock trial. Further, the magnitude of prospective jurors' distortion was twice that of students. Consistent with previous research, distortion increased with juror confidence in whichever verdict was currently leading. In spite of clear instructions to ignore prior beliefs, general proplaintiff or prodefendant attitudes influenced the verdicts of prospective jurors, but not of students. These findings suggest that jury instructions should warn against not only premature decisions but also any tentative judgments, lest such opinions influence jurors' evaluations of subsequent evidence. Predecisional distortion in jury trials may lead to biased outcomes resulting from evidence order effects.     

Effect of masker level on infants' detection of tones in noise

In adult listeners, the signal-to-noise ratio at masked threshold remains constant with increases in masker level over a wide range of stimulus conditions. This relationship was examined in 7-month-old infants by obtaining masked thresholds for .5- and 4-kHz tones presented in four levels of continuous masking noise. Adults were also tested for comparison. Masker spectrum levels ranged from 5 to 35 dB/Hz for .5-kHz tones, and from -5 to 25 dB/Hz for 4-kHz stimuli. Thresholds were determined for stimuli of both 10 and 100 msec in duration. The results indicated that infants' performance was more adult-like for 4-kHz stimuli. Although mean thresholds for both 10- and 100-msec, 4-kHz tones were approximately 7 dB higher in infants than in adults, E/N0 at threshold remained essentially constant over the 30-dB range of maskers employed. By contrast, infants' thresholds for .5-kHz tones were exceptionally high at lower levels of the masker. Threshold E/N0 decreased significantly as masker level increased from 5 to 35 dB/Hz, and this decrease was significantly greater for 10- than for 100-msec stimuli. Temporal summation of .5-kHz tones, measured as the difference between thresholds obtained at the two signal durations, was greater for infants than for adults at low levels of the masker. However, because infants' thresholds improved more rapidly with level for 10- than for 100-msec tones, age differences in temporal summation were no longer significant when masker spectrum level was 35 dB/Hz. These results suggest that the relationship between signal-to-noise ratio at masked threshold and level of the masker is dependent on both signal frequency and duration during infancy.     

Tops are more salient than bottoms.

Past research has verified that observers assume that objects are reliably oriented with respect to a gravitationally centered coordinate system. Observers also appear to attend more to specific parts of objects, like faces, that typically are closer to the top. In the present work, we explored whether or not observers have a generic bias to view tops as being more salient than bottoms. In three experiments, observers indicated whether random shapes appeared to be more similar to comparison shapes that shared identical tops rather than bottoms. Observers exhibited a reliable tendency to match figures with similarly shaped tops. Matching choice was also a function of global shape attributes such as axis of elongation or size. The findings are consistent with the notion that, in nature, tops tend to be the most visible part and to provide the best information with respect to important aspects of objects such as animal intentionality and artifact functionality.     

An event-based analysis of the coordination of early infant vocalizations and facial actions

This study used an event-based approach to provide empirical evidence regarding the nature of coordination in 3- and 6-month-old infants. Vocalizations and facial actions of 12 normally developing infants interacting with their caregivers were coded. Coded vocalizations and facial actions were considered coordinated when they temporally overlapped. Results indicate that infants coordinated their vocalizations and facial actions more than expected by chance. Coordinated events were governed by 2 sequence patterns. When 2 communicative events were temporally associated across modalities, 1 event tended to be completely embedded within the other, and vocalizations tended to end before facial actions. This study provides new information about how infant communication is structured, confirms results from other coordination studies, and describes a new method for analysis of event-based data.     

Planning ahead: goal-directed problem solving by 2-year-olds.

On tasks that require overcoming an obstacle along an existing path to a physically present goal, infants and very young children evince planning. In each of 3 experiments, the authors tested 21- and 27-month-olds' ability to construct a path to a mentally re-presented goal. Across experiments, the authors varied the number and type of cues to the solution provided. After exposure to the goal-state configuration of problems, both age groups showed evidence of planning (Experiment 1). Demonstration of the initial step in the solution path in Experiment 2 was not as effective as exposure to the goal state in Experiment 1. Even with specification of a greater proportion of the goal path, goal-state configuration information was particularly effective in facilitating performance (Experiment 3). The results suggest productive generation of solutions to novel problems by young children; planning is facilitated by goal-state configuration information.