Plasticity of the human auditory cortex induced by discrimination learning of non-native,mora-timed contrasts of the Japanese language

In this magnetoencephalographic (MEG) study, we examined with high temporal resolution the traces of learning in the speech-dominant left-hemispheric auditory cortex as a function of newly trained mora-timing. In Japanese, the “mora” is a temporal unit that divides words into almost isochronous segments (e.g., na-ka-mu-ra and to-o-kyo-o each comprises four mora). Changes in the brain responses of a group of German and Japanese subjects to differences in the mora structure of Japanese words were compared. German subjects performed a discrimination training in 10 sessions of 1.5 h each day. They learned to discriminate Japanese pairs of words (in a consonant, anni–ani; and a vowel, kiyo–kyo, condition), where the second word was shortened by one mora in eight steps of 15 msec each. A significant increase in learning performance, as reflected by behavioral measures, was observed, accompanied by a significant increase of the amplitude of the Mismatch Negativity Field (MMF). The German subjects' hit rate for detecting durational deviants increased by up to 35%. Reaction times and MMF latencies decreased significantly across training sessions. Japanese subjects showed a more sensitive MMF to smaller differences. Thus, even in young adults, perceptual learning of non-native mora-timing occurs rapidly and deeply. The enhanced behavioral and neurophysiological sensitivity found after training indicates a strong relationship between learning and (plastic) changes in the cortical substrate.     

Hippocampal damage and exploratory preferences in rats: memory for objects, places, and contexts

Rats have a natural tendency to spend more time exploring novel objects than familiar objects, and this preference can be used as an index of object recognition. Rats also show an exploratory preference for objects in locations where they have not previously encountered objects (an index of place memory) and for familiar objects in contexts different from those in which the objects were originally encountered (an index of context memory). In this experiment, rats with cytotoxic lesions of the hippocampal formation were tested on all three versions of the novelty-preference paradigm, with a 5-min retention interval between the familiarization and test phases. Rats with sham lesions displayed a novelty preference on all three trial types, whereas the rats with hippocampal lesions displayed a novelty preference on Object trials but did not discriminate between the objects on Place trials or Context trials. The findings indicate that hippocampal damage impairs memory for contextual or spatial aspects of an experience, whereas memory for objects that were part of the same experience are left relatively intact.     

A crossmodal attentional blink between vision and touch

There is currently a great deal of interest regarding the possible existence of a crossmodal attentional blink (AB) between audition and vision. The majority of evidence now suggests that no such crossmodal deficit exists unless a task switch is introduced. We report two experiments designed to investigate the existence of a crossmodal AB between vision and touch. Two masked targets were presented successively at variable interstimulus intervals. Participants had to respond either to both targets (experimental condition) or to just the second target (control condition). In Experiment 1, the order of target modality was blocked, and an AB was demonstrated when visual targets preceded tactile targets, but not when tactile targets preceded visual targets. In Experiment 2, target modality was mixed randomly, and a significant crossmodal AB was demonstrated in both directions between vision and touch. The contrast between our visuotactile results and those of previous audiovisual studies is discussed, as are the implications for current theories of the AB.     

The effect of similarity between elemental stimuli and compounds in olfactory patterning discriminations

We studied the ability of honeybees to discriminate between single odorants and binary olfactory mixtures. We analyzed the effect of the number of common elements between these two stimulus classes on olfactory discrimination. We used olfactory conditioning of the honeybees' proboscis extension reflex (PER), a paradigm in which odors can be associated with a reinforcement of sucrose solution. Bees were asked to discriminate reinforced from nonreinforced olfactory stimuli. They were trained with two elemental odors (A and B) versus a binary olfactory mixture. The mixture was either AB (group 2CE, two common elements), AC (group 1CE, one common element A), or CD (group 0CE, no common element). Three groups followed a positive patterning schedule (mixture reinforced and elements nonreinforced: groups 2CE+, 1CE+, and 0CE+) and three other groups a negative patterning schedule (mixture nonreinforced and elements reinforced: groups 2CE-, 1CE-, and 0CE-). We showed that a reduction of similarity (number of common elements) between elemental odors and compounds enhanced the ability to discriminate elements from compounds and that the kind of compound processing used by the bees supports theories that assume nonelemental compound processing (i.e., that exclude the mere summation of the elemental associative strengths upon compound presentation).     

Privileged access to action for objects relative to words

We compared action (pour or twist?) and contextual/semantic (found in kitchen?) decisions made to pictures of objects, nonobjects, and words. Although there was no advantage for objects over words in contextual/semantic decisions, there was an advantage for objects over words and nonobjects in action decisions. For objects, both action and contextual/semantic decisions were faster than naming; for words, the opposite occurred. These results extend the early results of Potter and Faulconer (1975) that there is privileged access to semantic memory for objects relative to that for words and privileged access to phonology for words. Our data suggest that, for objects, there is privileged access to action knowledge rather than to all forms of semantic knowledge and that this is contingent on learned associations between objects and actions.     

A direct measure of facial similarity and its relation to human similarity perceptions

Research is reported on a measure of facial similarity in which the similarity of 2 faces is defined as the Euclidean distance between them in a principal-component space. Five studies were conducted in which participants rated sets of facial images, and in which the measure was applied to 2 problems in the eyewitness literature. Comparisons of ratings with distances derived from the principal-component analysis suggest that the measure corresponds reasonably well to perceptions of facial similarity. In addition, the measure correlates strongly with empirical measures of lineup fairness and is related to eyewitness identification performance. Further potential applications include a software tool for constructing arrays of faces of varying similarity, and a software tool for reconstructing facial images from memory.     

Neuropsychological testing: evolution and emerging trends

Neuropsychological (NP) test batteries have evolved as an amalgam of intelligence tests, various individual measures of "biological" cognition, and sensory and motor testing. The early emphasis of NP testing was to identify "organicity" and central nervous system lesion localization. More recent approaches have emphasized the profiling of performance across individual neurocognitive domains (eg, attention, memory, and language) to facilitate diagnosis and treatment planning. However, the field is still hampered by the use of many tests that are antiquated, excessively long, or of dubious psychometric quality. Some of these problems may have contributed to the current under-utilization of NP testing in diagnostic workups of neuropsychiatric disorders. This paper reviews some of the recent changes in the field that hold promise for substantially shortening assessments, improving diagnostic reliability, and making NP testing more cost-effective and practical.     

Psychological and family factors associated with suicidal ideation in pre-adolescents

To assess the psychological and family factors associated with suicidal ideation in pre-adolescent children, we studied a sample of 361 students, average age 9 years old. Two groups were formed, on the basis of the presence (n = 34) or absence (n = 44) of suicidal ideation. Suicidal ideation was assessed with the Children's Depression Inventory and the Children's Depression Rating Scale-Revised. Depression, hopelessness, self-esteem, and perceived family environment were compared in both the suicidal ideation and the control groups. Students with suicidal ideation generally presented greater depressive symptoms and hopelessness, and lower self-esteem and family expressiveness, although there were differences both between sexes, and when the variable depression was controlled. Identifying these risk factors in pre-adolescents may have an impact on prevention of suicidal behavior at higher risk ages.     

Assessing the value of transgenic crops

In the current controversy about the value of transgenic crops, matters open to empirical inquiry are centrally at issue. One such matter is a key premise in a common argument (that I summarize) that transgenic crops should be considered to have universal value. The premise is that there are no alternative forms of agriculture available to enable the production of sufficient food to feed the world. The proponents of agroecology challenge it, claiming that agroecology provides an alternative, and they deny the claim that it is well founded on empirical evidence. It is, therefore, a matter of both social and scientific importance that this premise and the criticisms of it be investigated rigorously and empirically, so that the benefits and disadvantages of transgenic-intensive agriculture and agroecology can be compared in a reliable way. Conducting adequate investigation about the potential contribution of agroecology requires that the cultural conditions of its practice (and, thus, of the practices and movements of small-scale farmers in the "third world") be strengthened--and this puts the interests of investigation into tension with the socio-economic interests driving the development of transgenics. General issues about relationship between ethical argument and empirical (scientific) investigation are raised throughout the article.