Linear separability in superordinate natural language concepts

Two experiments are reported in which linear separability was investigated in superordinate natural language concept pairs (e.g., toiletry-sewing gear). Representations of the exemplars of semantically related concept pairs were derived in two to five dimensions using multidimensional scaling (MDS) of similarities based on possession of the concept features. Next, category membership, obtained from an exemplar generation study (in Experiment 1) and from a forced-choice classification task (in Experiment 2) was predicted from the coordinates of the MDS representation using log linear analysis. The results showed that all natural kind concept pairs were perfectly linearly separable, whereas artifact concept pairs showed several violations. Clear linear separability of natural language concept pairs is in line with independent cue models. The violations in the artifact pairs, however, yield clear evidence against the independent cue models.     

Text cohesion and metacomprehension: Immediate and delayed judgments

In three experiments, we examined comprehension judgments made after a piece of text had been read. We propose that such metacognitive judgments are based on the content of working memory at the exact moment of assessment. Generally speaking, this working metacognition hypothesis is in agreement with Koriat's cue utilization approach, which implies that different elements of information will be available (and used) depending on the moment at which a judgment is made. More specifically, our hypothesis focuses on the management of working memory during reading as a cause for cue (un)availability. In support of these views, the results of Experiment 1 showed that a cohesion manipulation affecting the comprehension of specific paragraphs influences judgments only on these paragraphs, and not on judgments on the whole text. In Experiment 2, we showed that an interfering task that takes place just before this paragraph judgment is made wipes out this cohesion effect. Experiment 3 showed, on the other hand, that the whole-text judgment may, nevertheless, be affected by text cohesion, provided that the readers keep an access to the text when the judgment is made. These results support the idea that working memory management makes different cues available for metacognitive ratings at different delays.     

Anticipatory balance control is affected by loadless training experiences

The main purpose of this study was to identify whether a lot of sports training had any effect on the balance control associated with a leg movement. The nature of the training experience was also an important concern and we chose subject who had undergone specific training experience in absence of equilibrium constraints. To this end a comparison between control (untrained) subjects, triathletes and swimmers was designed to establish whether a general training in sports (triathletes) or a specific loadless training (swimmers), leads to differences in the balance control. A leg movement is preceded by a shift of the center of mass (CM) towards the supporting side to maintain equilibrium and forward to create the condition for progression. To provide an acceleration of the CM sideward and forward, an initial displacement of the center of pressure (CP) towards the moving limb and in posterior direction was performed. Interestingly, the lateral pressure onto the ground was greater increased in swimmers in both leg raising and obstacle avoidance tasks compared to the control group and/or triathletes whereas the backward CP shift in all group was the same. The initial control of the CM shift is very different in swimmers compared to triathletes and controls. The increased lateral pressure onto the ground in swimmers may be a result of a prolonged training in water. This suggests that prolonged training in the absence of equilibrium constraints has more of an effect on balance control than a prolonged general training. In addition, the lack of differences in the backward CP shift suggests that M/L and A/P controls support two functional goals: equilibrium maintenance and movement initiation.     

Sex differences for selective forms of spatial memory

In the present study, a systematic comparison of sex differences for several tests of spatial memory was conducted. Clear evidence for more accurate male performance was obtained for precise metric positional information in a wayfinding task and in an object location memory task. In contrast, no sex difference characterized topological information processing (object-to-position assignment). Together, these findings provide further insight in the specificity of sex differences in spatial memory and in the functional architecture of spatial memory. Implications for the relevant evolutionary basis are discussed.     

Bilingualism and adult differences in inhibitory mechanisms: evidence from a bilingual stroop task

The present investigation examined the functioning of inhibitory mechanisms in younger and older bilinguals using a bilingual version of the Stroop test. The study predicted different patterns of age related decline in inhibitory mechanisms (inter- and intralingual interference) in bilinguals depending on their level of proficiency. Consistent with expectations, older bilinguals were slower when they responded in their non-dominant language. Furthermore, older unbalanced bilinguals showed greater interlingual interference when they responded with their second language to visual stimuli written in their dominant language. Balanced bilinguals showed equivalent interference effects between all conditions. These findings suggest that manipulating two languages may enhance the efficiency of inhibitory mechanisms.     

A diffusion model analysis of the effects of aging in the lexical-decision task

The effects of aging on response time (RT) are examined in 2 lexical-decision experiments with young and older subjects (age 60-75). The results show that the older subjects were slower than the young subjects, but more accurate. R. Ratcliff s (1978) diffusion model provided a good account of RTs, their distributions, and response accuracy. The fits show an 80-100-ms slowing of the nondecision components of RT for older subjects relative to young subjects and more conservative decision criterion settings for older subjects than for young subjects. The rates of accumulation of evidence were not significantly different for older compared with young subjects (less than 2% and 5% higher for older subjects relative to young subjects in the 2 experiments).     

Learning at a distance II. Statistical learning of non-adjacent dependencies in a non-human primate

In earlier work we have shown that adults, infants, and cotton-top tamarin monkeys are capable of computing the probability with which syllables occur in particular orders in rapidly presented streams of human speech, and of using these probabilities to group adjacent syllables into word-like units. We have also investigated adults' learning of regularities among elements that are not adjacent, and have found strong selectivities in their ability to learn various kinds of non-adjacent regularities. In the present paper we investigate the learning of these same non-adjacent regularities in tamarin monkeys, using the same materials and familiarization methods. Three types of languages were constructed. In one, words were formed by statistical regularities between non-adjacent syllables. Words contained predictable relations between syllables 1 and 3; syllable 2 varied. In a second type of language, words were formed by statistical regularities between non-adjacent segments. Words contained predictable relations between consonants; the vowels varied. In a third type of language, also formed by regularities between non-adjacent segments, words contained predictable relations between vowels; the consonants varied. Tamarin monkeys were exposed to these languages in the same fashion as adults (21 min of exposure to a continuous speech stream) and were then tested in a playback paradigm measuring spontaneous looking (no reinforcement). Adult subjects learned the second and third types of language easily, but failed to learn the first. However, tamarin monkeys showed a different pattern, learning the first and third type of languages but not the second. These differences held up over multiple replications, using different sounds instantiating each of the patterns. These results suggest differences among learners in the elementary units perceived in speech (syllables, consonants, and vowels) and/or the distance over which such units can be related, and therefore differences among learners in the types of patterned regularities they can acquire. Such studies with tamarins open interesting questions about the perceptual and computational capacities of human learners that may be essential for language acquisition, and how they may differ from those of non-human primates.