Joint control strategies and hand trajectories in multijoint pointing movements

The role of timing in the control of multijoint pointing movements was evaluated. Eight subjects performed rapid pointing movements to a variety of target locations. The subject's right arm was strapped to a 2 degrees of freedom manupilandum that permitted shoulder and elbow motion in the horizontal plane. Initial and final position of the hand and magnitude of displacement was varied to determine effects on timing characteristics. Kinematics and kinetics of the shoulder, elbow, and hand were analyzed. The hand paths and velocity profiles observed were consistent with prior reports. Multiple regression analysis of kinematic variables disclosed that timing of joint movement onset was independent of initial and final positions of the hand, but was linearly related to joint displacement: the joint that moved farther started moving first. Using computer simulations to create joint movement onset, times that were different from the observed ones always resulted in hand paths with increased curvatures and loss of the smooth velocity profiles. Secondly, a very stable, linear relationship was observed between peak velocity and displacement at both the elbow and shoulder joints. This relationship was not affected by variations in movement space. We suggest that space-time transformation based on difference in joint displacement is used to regulated timing of joint movement onset. The simulations indicate that this transformation is set to produce smooth velocity profiles. The relationships between timing of movement onset and displacement and between peak velocity and displacement complement each other: by maintaining a linear relationship between velocity and displacement, a linear space time transformation can be used to control timing. Furthermore, these relationships are probably used to simplify coordination between the moving joints.     

JUST WHAT ARE SEX AND GENDER, ANYWAY?

Abstract— The terms sex and gender have come to be used as synonyms in the social sciences literature. However, nothing has been gained by the use of the term gender except confusion. This article identifies five meanings for which social scientists often use the terms sex or gender and proposes a distinct term for each of those five meanings. The terms proposed are (1) sex: to refer to the biological function; (2) biologically sex-linked: to refer to traits or conditions that are causally biologically related to being male or female; (3) gender-linked: to refer to traits or conditions that are causally linked with maleness or femaleness but are culturally based as opposed to biologically based; (4) sex- and gender-linked: to refer to traits or conditions that are causally related to both a biological component and a cultural component; and (5) sex-correlated: to refer to traits or conditions that are related to being male or female without asserting a causal relation to either biology or culture (because we do not wish to make such an assertion or cannot do so confidently). It is hoped that adopting a terminological standard will reduce the confusion resulting from nonspecific language use.     

Use of the computer and Internet among Italian families: first national study.

Although home Internet access has continued to increase, little is known about actual usage patterns in homes. This nationally representative study of over 4,700 Italian households with children measured computer and Internet use of each family member across 3 months. Data on actual computer and Internet usage were collected by Nielsen//NetRatings service and provide national baseline information on several variables for several age groups separately, including children, adolescents, and adult men and women. National averages are shown for the average amount of time spent using computers and on the Web, the percentage of each age group online, and the types of Web sites viewed. Overall, about one-third of children ages 2 to 11, three-fourths of adolescents and adult women, and over four-fifths of adult men access the Internet each month. Children spend an average of 22 hours/month on the computer, with a jump to 87 hours/month for adolescents. Adult women spend less time (about 60 hours/month), and adult men spend more (over 100). The types of Web sites visited are reported, including the top five for each age group. In general, search engines and Web portals are the top sites visited, regardless of age group. These data provide a baseline for comparisons across time and cultures.     

Religion and the Limits of Liberalism

This is the editors' preface to a special issue of Philosophia on 'Religion and Limits of Liberalism'. It begins by noting the challenges which the 'return' of religions to liberal democracies poses to the liberal commitment to respect citizens’ freedom and equality. Then, with particular reference to Rawls' theory of liberal politics, it situates the papers in relation to three different senses of liberal ‘respect’ that are challenged by contemporary religions – one understood in terms of the justification of political power, another as tolerance of diversity, and the third in terms of freedom from interference.     

Where the brain appreciates the final state of an event: The neural correlates of telicity

In this study we investigated whether the human brain distinguishes between telic events that necessarily entail a specified endpoint (e.g., reaching), and atelic events with no delimitation or final state (e.g., chasing). We used functional magnetic resonance imaging to explore the patterns of neural response associated with verbs denoting telic and atelic events, and found that the left posterior middle temporal gyrus (pMTG), an area consistently engaged by verb processing tasks, showed a significantly higher activation for telic compared with atelic verbs. These results provide the first evidence that the human brain appreciates whether events lead to an end or a change of state. Moreover, they provide an explanation for the long-debated question of which verb properties modulate neural activity in the left pMTG, as they indicate that, independently of any other semantic property, verb processing and event knowledge in this area are specifically related to the representation of telicity.     

Reprint of: stuttering treatment control using P300 event-related potentials

Positron emission tomography studies during speech have indicated a failure to show the normal activation of auditory cortical areas in stuttering individuals. In the present study, P300 event-related potentials were used to investigate possible effects of behavioral treatment on the pattern of signal amplitude and latency between waves. In order to compare variations in P300 measurements, a control group paired by age and gender to the group of stutterers, was included in the study. Findings suggest that the group of stutterers presented a significant decrease in stuttering severity after the fluency treatment program. Regarding P300 measurements, stutterers and their controls presented results within normal limits in all testing situations and no significant statistical variations between pre and post treatment testing. When comparing individual results between the testing situations, stutterers presented a higher average decrease in wave latency for the right ear following treatment. The results are discussed in light of previous P300 event-related potentials and functional imaging studies with stuttering adults.Educational objectives: The reader will learn about and be able to describe the: (1) use of P300 event-related potentials in the study of stuttering; (2) differences between stuttering and non-stuttering adults; and (3) effects of behavioral fluency treatment on cerebral activity in stuttering speakers.     

Infants' discrimination of happy and sad music

Infants can detect information specifying affect in infant- and adult-directed speech, familiar and unfamiliar facial expressions, and in point-light displays of facial expressions. We examined 3-, 5-, 7-, and 9-month-olds' discrimination of musical excerpts judged by adults and preschoolers as happy and sad. In Experiment 1, using an infant-controlled habituation procedure, 3-, 5-, 7-, and 9-month-olds heard three musical excerpts that were rated as either happy or sad. Following habituation, infants were presented with two new musical excerpts from the other affect group. Nine-month-olds discriminated the musical excerpts rated as affectively different. Five- and seven-month-olds discriminated the happy and sad excerpts when they were habituated to sad excerpts but not when they were habituated to happy excerpts. Three-month-olds showed no evidence of discriminating the sad and happy excerpts. In Experiment 2, 5-, 7-, and 9-month-olds were presented with two new musical excerpts from the same affective group as the habituation excerpts. At no age did infants discriminate these novel, yet affectively similar, musical excerpts. In Experiment 3, we examined 5-, 7-, and 9-month-olds' discrimination of individual excerpts rated as affectively similar. Only the 9-month-olds discriminated the affectively similar individual excerpts. Results are discussed in terms of infants' ability to discriminate affect across a variety of events and its relevance for later social-communicative development.     

Assessing students' use of optional online lecture reviews

Online practice quizzes can be used to supplement instruction in the classroom. Such quizzes can engage retrieval practice, thereby improving learning and retention. However, despite their potential benefits, recent work suggests that students typically underutilize online practice quizzes. This article reports an observational classroom study, in which students were provided optional online reviews throughout the semester. The reviews could be accessed in test format, in which students were given multiple-choice questions and provided correct answer feedback, or in read format in which students were given the same questions and were shown the correct answers. Students who used the test format performed better on exams than students who used the read format or did not use the reviews. Nevertheless, the massive majority of the online reviews (approximately 88%) were not completed, highlighting the tendency for students to underutilize optional online reviews.