3 resultados para Difference frequency generation (DFG)

em Brock University, Canada


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One hundred and five primarily Caucasian undergraduate couples were tested to study the phenomenon of attitude alignment, or the way in which individuals change their opinions to achieve greater attitudinal congruence with their romantic partners, and the hypotheses that relationship closeness, affect, attachment, social desirability, and centrality are each related to attitude alignment for individuals in close couples. The couples filled out an attitude questionnaire consisting of 50 issues in which they were asked to give their attitude on a scale from 1 to 9 as well as to rate the centrality, or importance, of that issue on a scale from 1 to 9. Before discussing four of these issues with each other - 2 were more central to the man and less central, or peripheral, to the woman, whereas the other 2 were central to the woman and peripheral to the man - the individuals completed established measures of relationship closeness, affect, attachment, and social desirability. The couples then filled out the identical attitudes questionnaire again, and their answers on the four discussion issues were compared to their prediscussion answers to determine whether attitude alignment had occurred. There were two experimental groups: a social desirability group, where the couples were told it was natural and normal to disagree with their partners, and a control group. Results indicated that attitude alignment did significantly occur across all couples, but most other variables - including centrality, relationship closeness, and affect - did not predict attitude alignment behaviour. As well, the social desirability experimental groups did not significantly differ on attitude alignment behaviours, but higher scores on the social desirability scale, specifically self-deception, significantly predicted higher attitude alignment scores across all couples. Large differences between individuals' frequency.

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A class of twenty-two grade one children was tested to determine their reading levels using the Stanford Diagnostic Reading Achievement Test. Based on these results and teacher input the students were paired according to reading ability. The students ages ranged from six years four months to seven years four months at the commencement of the study. Eleven children were assigned to the language experience group and their partners became the text group. Each member of the language experience group generated a list of eight to be learned words. The treatment consisted of exposing the student to a given word three times per session for ten sessions, over a period of five days. The dependent variables consisted of word identification speed, word identification accuracy, and word recognition accuracy. Each member of the text group followed the same procedure using his/her partner's list of words. Upon completion of this training, the entire process was repeated with members of the text group from the first part becoming members of the language experience group and vice versa. The results suggest that generally speaking language experience words are identified faster than text words but that there is no difference in the rate at which these words are learned. Language experience words may be identified faster because the auditory-semantic information is more readily available in them than in text words. The rate of learning in both types of words, however, may be dictated by the orthography of the to be learned word.

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There is extensive evidence that the mesolimbic dopamine system underlies the production of 50 kHz ultrasonic vocalizations in rats. In particular, the shell of the nucleus accumbens is associated with generation of frequency modulated 50 kHz calls (a specific type of 50 kHz call which can be subdivided into various subtypes). There is also evidence that amphetamine administered systemically preferentially increases the proportion of trill and step calls compared to other frequency modulated 50 kHz subtypes. The purpose of this study was to investigate the effect of drug administration route and the role of the nucleus accumbens shell in amphetamine-induced 50 kHz call profile in the rat. Three experiments investigated this by using subcutaneous and intra-accumbens microinjections of amphetamine, as well as procaine (a local anesthetic) blockade of the nucleus accumbens. Ultrasonic vocalizations were recorded digitally from 24 rats and were analysed for sonographic structure based on general call parameters. The results of the three experiments were partially supportive of the hypotheses. Systemic amphetamine was found to induce greater bandwidth in 50 kHz calling compared to spontaneous calls in a vehicle condition. Systemic amphetamine was also found to preferentially increase the proportion of trill and step subtypes compared to vehicle. Moreover, there was no difference in the proportions of 50 kHz subtypes resulting from intracerebral or systemic application of amphetamine. There was, however, a significant difference for bandwidth, with systemic amphetamine inducing greater bandwidth over intraaccumbens application. Procaine blockade of the nucleus accumbens shell paired with subcutaneous amphetamine produced no difference in bandwidth of calls compared with those after a vehicle pre-treatment similarly paired. There was no reduction in the proportions of trill and step 50 kHz subtypes as well, with the procaine condition showing significantly greater proportion of step calls. The results of the study support a role for the iii nucleus accumbens shell in the amphetamine-induced changes on 50 kHz call profile. They also indicate there are more regions and pathways involved in generating 50 kHz calls than the projections from the ventral tegmental area to the nucleus accumbens. The implications of this work are that frequency modulated 50 kHz subtypes may be generated by distinct neurophysiological mechanisms and may represent a profitable avenue for investigating different circuits of 50 kHz call categories in the rat.