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- P-ISSN1226-9654
- E-ISSN2733-466X
- KCI
ISSN : 1226-9654
Vol.8 No.1
Abstract
Four experiments were conducted to examine the role of phonological rules in Korean word recognition. Regular and irregular Hangul strings were employed. There was strict grapheme-phoneme correspondence in the regular strings. But pronunciation of irregular strings could not be computed by using grapheme-phoneme correspondence. In Experiment 1 and 2, naming times for irregular words and nonwords were shorter than for appropriate controls. But this effect was restricted to lower frequency words and nonwords. The result indicates psychological reality of phonological rules in Korean. In Experiment 3, naming times for pseudohomophones were shorter than for controls. The result indicates phonologically mediated lexical-access route in Korean. In Experiment 4 using a lexical decision task, the regularity effects were also found for lower frequency words, but pseudohomophone effects were not found. These results are discussed in terms of their implications for dual route model.
Abstract
Following the seminal reports on genes affecting human personality in 1996, explosive number of reports relating genes and behavioral traits in higher mammals are expected to be witnessed in the near future. Successful genetic explanation of behavioral variablity should include mechanisms by which genotypes affecting behaviors are expressed. We reviewed controlled studies on canine behavioral genetics and proposed that canine behavioral genetics can be used as an experimental model for investigating the expression mechanisms of genes in determining the variablity of behavioral phenotypes in higher mammals. Problems in establishing inheritance factors in previous studies were discussed: 1) insufficient information on perceptual mechanisms of animal subjects, 2) subjective and imprecise measurement of animal behavior, 3) uncontrolled interactions between animals and experimenters. Suggestions were made for more rigorous studies of canine behavioral genetics: 1) identifying behavioral traits and indices reflecting genetic background, 2) precise measurement of behavior, 3) accumulating informations on dog genome.
Abstract
An important issue in reading research concerns the role of phonology in word recognition. While some authors believe that phonology plays a minor role in word recognition, others believe that word recognition is always mediated by its phonology. Using Korean words, the present study examined the possibility of phonological mediation in lexical access. Experiment 1 examined whether pseudohomophone primes (eg. 나겹) facilitate recognition of their semantic associatives (eg. 가을) as much as their real word counter parts (eg. 낙엽) do in a lexical decision task. The result showed a marginally significant pseudohomophone priming effect, and its magnitude was smaller than that of real word priming effect. Experiment 2 explored homophone's negative effect. After presenting each pair of words, subjects were asked to decide whether they were semantically related. One word of each pair had the same phonology as the word associated semantically with the other word of the pair (eg. 가치-함께; 같이-쓸모). The rate of false positive responses was significantly higher than their visual controls (eg. 갈이-함께; 가지-함께). Taken together, these results indicate that phonology plays some, but not dominant, role in Hangul word recognition.
Abstract
In this study we examined the temporal relationships of the eye movement-related activities of the visual cortical areas 17 and 18 with the saccade onset and offset times in three awake cats. Eye positions were monitored with the scleral search-coil technique, and single or multiple unit activities were recorded with conventional electrophysiological methods while cats were spontaneously making saccades in the dark. Saccade onset and offset times were determined according to velocity criteria. Based on the sequence of action potentials, the spike probability density was estimated by a variable kernel method and the onset of neural activity was determined with a spike density threshold. When all 666 saccade-related activities of 59 recording sites were combined, the lag between the onset of neural activity and the saccade onset time was linearly correlated with saccade duration(slope of linear regression line was 1.01). On the other hand, the lag between the onset of neural activity and the saccade offset was independent of saccade duration(slope of linear regression line was 0.01), with the saccade offset leading the onset of neural activity by 46ms on average. Thus, eye movement-related cortical activity was more tightly related to saccade offset than onset time. These results suggested that the eye movement-related signals integrated in the visual cortex might play a perceptual role rather than corollary discharge of eye movement commands as previously assumed.
Abstract
This study was conducted to examine the role of medial and lateral septum in expression of anxiety in rats. Effects of medial and lateral septal lesions were compared in an elevated plus-maze. Rats were divided into sham-operated, medial septal lesions and lateral septal lesions. Half of the animals in each group were administered 2mg/kg diazepam 20 minutes prior to the plus-maze test. Injection of diazepam increased open-arm exploration in sham-operated animals. Septal lesions increased open-arm exploration, but there was no difference in performance between medial and lateral lesions. This results suggested the septum control the expression of anxiety, but the proposition that medial septum and the lateral septum indepedently control the expression of anxiety was not supported.
Abstract
Two experiments were performed to investigate the effects of category size and item discriminability on the rule extraction and storage of exemplar information in learning of rule-described categories. In both experiments MDS-solutions based on the MDS-choice model were obtained from the data of item identification task, and categorization data were obtained using the typical learning-transfer phase paradigm. In Experiment 1, category size was increased up to 16 items per category. Compared to the results of previous research, it seems that tendency to extract rules increases as the category size becomes large. In Experiment 2, discrimination cues to increase the discriminability among the items were given to the subjects. The results showed that a tendency to extract and use rules in learning categories and categorizing new items increase in the case of high discriminability among the items. It was suggested that many factors, conditions, or constraints can affect learning various kinds of categories including rule-described categories.
Abstract
Depression is often related with memory impairment. The present study used the passive avoidance conditioning to evaluate the effects of fluoxetine on the retention of memory in an animal model of depression. Chronic exposure to a variety of mild unpredictable stress such as loud noise, flash light, or restriction of food and water, causes several behavioral symptoms correspondent to those of depression. Rats in experimental groups were exposed chronic mild stress(CMS) during 8 weeks, and monitored the consumption of 1% sucrose solution every week as a index of depression. After 4 weeks of CMS exposure they received the training trials of passive avoidance conditioning, and during next 4 weeks they received the retention tests weekly with drug treatment. On the basis of sucrose intake of 4th week they were devided two matched subgroups, and during latter 4 weeks each group daily treated with fluoxetine(15mg/kg) or saline. CMS exposure reduced the sucrose consumption gradually in the first 4 weeks. This effect was reversed after 3 weeks of fluoxetine treatment. In the training trials, experimental groups showed lower acquisition scores than control (no stress) groups and in the 3week-retention trial, saline-experimental group performed more poorly than saline-control group. This is, CMS exposure impaired the learning and memory processing of animals. Fluoxetine-experimental group showed better retention of memory than saline-experimental group in the 3week-retention trial, and fluoxetine-control group also performed better than saline-control group in the 4week-retention trial. These results suggest that fluoxetine, the representative selective serotonin reuptake inhibitor, has positive effects on memory improvement as well as antidepressant effects.
Abstract
In an attempt to investigate that individual differences in working memory capacity, as measured by the reading span test (Daneman & Carpenter, 1980; Lee, 1995), would result in different patterns of language processing, three experiments were carried out. In experiment 1, our high span and low span subjects were required to perform the dual task in which spatial inference from referentially continuous and discontinuous descriptions were performed concurrently with the memory task with different loads. In experiment 2, self-paced reading times were measured for the sentences with different relative clause constructions of SOV/OO and OSV/SO. In experiment 3 adopting Gernsbacher, Varner and Faust's (1990) paradigm to our subjects, reaction times were measured for accepting conceptually appropriate meaning of an ambiguous word as well as for rejecting inappropriate meaning. In all these experiments significant differences in the various tasks were observed between the high-span and low span readers. More important, putting the results of experiment 1 and 2 together provides the evidence that low span readers showed the marked processing cost whenever there was an additional load while high span readers did not. And putting the results of experiment 2 and 3 together provides the evidence that low span readers showed the spill-over effects during processing in both tasks of the sentence reading and the decision on accepting the appropriate meaning while the immediacy of integration occurred for high span readers. We discussed that these data patterns seriously question Just and Carpenter's (1992) assumption that high span and low span readers perform the same operations and that individual differences are inherent in the total capacity of working memory. Instead, it may be the case that high span readers have the function of working memory which is assumed to be capable of governing and operating the processing efficiency and the sophisticated processing strategies that low span readers lack.
Abstract
Event-related potentials were recorded from normal subjects in an auditory selective attention task. The focus of this study was the effect of processing load on event-related potentials(ERPs). Subjects were instructed to selectively attend to tones of designated ear and to respond to those that were higher in frequency by pressing a corresponding response button. Processing load was manipulated by the difficulty level of discrimination between standards and deviants. The standard stimuli were 1000Hz, 60dB SPL, tone burst. The deviant stimuli were only differed in frequency. In the easy task condition, the deviant stimuli were 1500Hz and in the hard task condition, they were 1050Hz. Performance was more accurate and faster in the easy task. These results show that the task condition was reliable. Attention effect(Nd) to standard stimuli peaked at approximately 240msec with a maximal amplitude at Fz. The latency of Nd was dissociated from that of N1. Thus we can conclude that the attention effect was not caused by N1 enhancement but by the activity of processing negativity(PN). The task effect was appeared to the later ERP components. The amplitude of P3b was decreased in the hard task as in previous studies. The result showing the ineffectiveness of attention on N1 suggests that the process to analyze physical features of auditory stimulus can be automatic. The task effect was shown only on the later components of the ERP, therfore we can conclude that the processing load does influence in the later stages of auditory stimulus processing.
Abstract
The purpose of this study was to test the relative validity of the dominance structure search model in comparison with the two-stage models which had been proposed to explain decision process.. The search for a dominance structure is assumed to go through four phases, viz. pre-editing, finding a promising alternative, dominance testing, and dominance structuring. Experiment 1 tested whether or not the number of attributes searched in the initial stage of decision making were determined by the limited capacity of information processing. The results indicate that the number of attribute information searched in the initial stage of decision making is determined within the limited capacity. Experiment 2 was conducted to test the assumption of the dominance search model, that a certain promising alternative is selected tentatively after the pre-editing stage and this alternative has high likelihood to be selected later finally. The results showed that regardless of the number of dominant alternatives, the selection rate of the promising alternative was about 75% of all trials and of the alternative was selected finally 85% of the times even in competitive situation. In Experiment 3, the evidences for the dominance testing process and the dominance structuring process were investigated. The results revealed that both important and unimportant attributes were searched before the final choice and all conflicting attributes became the objects of conflict-resolution operation, regardless of the attribute importance. Experiment 4 tested whether or not the given information (e.g., attribute importance and attractiveness of attribute values) was restructured in the direction that a selected alternative might be dominant than competitive ones by means of the de-emphasizing and the bolstering operation in the case of interalternatives conflict. The results showed that the importance of dominant attributes in the selected alternative was bolstered more strongly in a post-decision than in a pre-decision, however, the importance of the dominant attributes in the competitive ones was de-emphasized much more low. The result on the attractiveness evaluation of attribute values showed that the evauation of attractiveness of attribute values in the competitive ones was not changed in the decision process, however, the attractiveness evaluation of attribute values in the selected one was bolstered more strongly. In summary, the results suggest that the dominance search model can explain the decision process very well in comparison with the two-stages models, a decision is made generally via the stages assumed in the dominance search model.