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1.
Five experiments tested the effects of experience with a white compartment not paired with footshock (CS?) on conditioning of an aversion to a black compartment paired with footshock. As previously found with odors as CSs, a single pairing of the CS+ with footshock yielded significant conditioning only if the animal was also exposed to CS?, with greater conditioning when the CS? exposure preceded the CS+ than when the CS+ preceded the CS?. If, however, the CS? preceded CS+ by a 24-h interval, it was ineffective and no CS+ conditioning occurred. For adult rats, the effectiveness of the CS?/CS+ “integration” progressively decreased with increasing length of the interval separating their occurrence, although it was still significant (i.e., some CS+ conditioning occurred) with a 12-h CS? to CS+ delay. For preweanlings (16 days postnatal), no conditioning to CS+ occurred if the interval between CS? and CS+ was 1 h or longer, although significant conditioning to CS+ did occur with a CS? to CS+ interval as long as 40 min. It was as if active memory for the CS? at the time of CS+ exposure was necessary for CS+ conditioning, and forgetting of the CS? memory proceeded more rapidly for preweanling than for adult rats. Collectively, these experiments extend results previously indicating that (1) the CS+ contiguous to the US may or may not be “selected” for conditioning, depending on the rat’s exposure to, or memory for, a CS?, and (2) this stimulus selection might differ for immature and mature rats. 相似文献
2.
In two experiments with rats as subjects, the temporal characteristics of inhibition produced through extinction were investigated.
Each experiment established two independent signals for unconditioned stimulus presentation, one trace and one delay. Following
initial training, either the trace or the delay conditioned stimulus (CS) was massively extinguished. In Experiment 1, a summation
test established that an extinguished delay CS (but not a neutral CS) passed a summation test with a delay, but not with a
trace, transfer excitor, and an extinguished trace CS (but not a neutral CS) passed a summation test with a trace, but not
with a delay, transfer excitor. In Experiment 2, a retardation test showed retarded behavioral control by an extinguished
delay CS when the CS was retrained as a delay CS, but not as a trace CS, and by an extinguished trace CS when the CS was retrained
as a trace CS, but not as a delay CS. The results are discussed in terms of contemporary theories of extinction. 相似文献
3.
Conditioned lick suppression in rats was used to explore the role of timing in trace conditioning. In Experiment 1, two groups of rats were exposed to pairings of a CS (CS1) with a US, under conditions in which the interstimulus interval (ISI) that separated CS1 offset and US onset was either 0 or 5 sec. Two additional groups were also exposed to the same CS1→US pairings with either a 0 or a 5-sec ISI, and then received “backward” second-order conditioning in which CS1 was immediately followed by a novel CS2 (i.e., CS1→CS2). A trace conditioning deficit was observed in that the CS1 conditioned with the 5-sec gap supported less excitatory responding than the CS1 conditioned with the 0-sec gap. However, CS2 elicited more conditioned responding in the group trained with the 5-sec CS1-US gap than in the group trained with the 0-sec CS1-US gap. Thus, the CS1-US interval had inverse effects on first- and second-order conditioned responding. Experiment 2 was conducted as a sensory preconditioning analogue to Experiment 1. In Experiment 2, rats received the CS1?CS2 pairings prior to the CS1→US pairings (in which CS1 was again conditioned with either a 0 or a 5-sec ISI). Experiment 2 showed a dissociation between first- and second-order conditioned responding similar to that observed in Experiment 1. These outcomes are not compatible with the view that differences in responding to CSs conditioned with different ISIs are mediated exclusively by differences in associative value. The results are discussed in the framework of the temporal coding hypothesis, according to which temporal relationships between events are encoded in elementary associations. 相似文献
4.
Despite the current growing popularity of the computer science (CS) major, women remain sorely underrepresented in the field, continuing to earn only 18% of bachelor’s degrees. Understanding women’s low rates of participation in CS is important given that the demand for individuals with CS training has grown sharply in recent years. Attracting and retaining more women to high-paying fields like CS may also help narrow the gender pay gap. Further, it is important that women participate in developing new technology so that technology advances serve the needs of both women and men. This paper explores the background characteristics, career aspirations, and self-perceptions of 1636 female first-year college students in the United States who intend to major in CS and compares them with 4402 male CS aspirants as well as with 26,642 women planning to major in other STEM sub-fields. The findings reveal a unique profile of women who pursue the CS major and notes many significant differences between men and women in CS and between women in CS and those in other STEM fields. For instance, women in CS tend to earn lower high school grades than women in other STEM fields, but earn higher SAT verbal scores. They also rate themselves higher than men in CS and women in other STEM fields on measures of their artistic ability, but rate themselves lower on other self-ratings, including academic and leadership ability. Further, women in CS are more likely to be undecided in their career plans than men in CS and women in other STEM fields. Understanding the unique characteristics of women in CS will help inform policies and recruitment programs designed to address the gender gap in computing. 相似文献
5.
在市场竞争日益加剧的今天，CS战略即是企业可以利用去争取竞争优势的一个重要砝码，本文通过解析CS，提出实施CS势在必行，并由此提出CS质量指标体系构建的基础和过程以及全面创建CS的方法。 相似文献
6.
Prior cuing treatments intended to alleviate the forgetting of a conditioned avexsion-to an odor were tested with 18-day-old rats. Previous experiments had shown that when such pups were conditioned with the use of a CS?/CS+ procedure, pretest presentation of the CS? or US, but not the CS+, alleviated the forgetting otherwise seen after a 3-h retention interval. In Experiment 1, it was determined that the forgetting was not alleviated if the GS? was either preceded or followed by presentation of the CS+, despite the fact that the CS?/CS+ ordering mimicked that of original conditioning. Experiment 2 was an examination of the balance of extinction and reactivation effects caused by presenting the CS+ for varying durations following the 3-h retention interval. The forgetting over this interval was alleviated if the CS+ was presented for 5 or 15 sec, but not 30 sec. With an increase in duration of exposure from 15 to 30 sec, the consequences of the CS+ as a prior cuing treatment apparently shifted from reactivation to extinction. Experiment 3 was a test of the interaction between the consequences of different lengths of CS+ exposure and the effectiveness of adding CS? to the CS+ as a reactivation treatment. The varied effectiveness of reactivation treatments is discussed interms of a change in stimulus conditions from training to reactivation. 相似文献
7.
The purpose of this mixed methods study was to examine ways to promote computer science (CS) among girls by exploring young women’s experiences and perceptions of CS as well as investigating factors affecting their career aspirations. American girls aged 10–16 participated in focus group interviews as well as pre-, post-, and follow-up surveys while attending a CS camp. The analysis of data revealed that although the participants were generally positive about the CS field, they had very limited knowledge of and experience with CS, leading to little aspiration to become computer scientists. The findings also indicated that girls’ affinity for and confidence in CS were critical factors affecting their motivation for pursuing a CS-related career. The study demonstrated that participation in the CS camp motivated a small number of participants to be interested in majoring in CS, but the activity time was too short to make a significant impact. Based on the findings, we suggest that providing CS programming experiences in K-12 classrooms is important in order to boost girls’ confidence and interest in CS. 相似文献
8.
Male albino rats were exposed to negative correlations of tone CSs and shock USs. When the number of CSs and unpaired USs was held constant, the ability of the CS to resist subsequent excitatory conditioning declined as a function of the number or proportion of CSs paired with USs; so, too, did the ability of the CS to disrupt excitation to a second CS. In one treatment, in which the rate of USs in CS presence approached that in CS absence, the CS significantly enhanced excitation to a second CS. It is concluded that the rate of USs in CS presence need not be zero for a negative correlation to produce inhibitory effects. Also discussed is the possibility that positive and negative correlation procedures may have asymmetrical effects, at least preasymptotically. 相似文献
9.
The present research examined the temporal distribution of responding in a lick suppression paradigm. In Experiment 1, rats were trained with either a 30- or a 120-s conditioned stimulus (CS), which was followed either by a footshock (unconditioned
stimulus [US]) or nothing. Licking during the CS was suppressed only in the former condition. Suppression was more pronounced
early in the CS. In Experiment 2, rats were exposed to two 30-s or two 120-s CSs, with delivery of the shock being contingent on CS1 for half of the animals
and on CS2 for the other half. For both the paired and the unpaired conditions, suppression at the beginning of CS1 was observed
for all the groups. By discounting the possibility of generalization between CS1 and CS2, it appears that this initial suppression
was not a conditioned response to the CS, but an unconditioned one due to mere exposure to the shock US. 相似文献
10.
Animals were first conditioned to expect lithium treatment following exposure to one taste solution (the CS+) and to expect no drug treatment following exposure to another flavor (the CS?). All subjects then received a saccharin taste-aversion conditioning trial. In Experiment 1, this conditioning trial was preceded 0, 1, 2, 4, or 6 h earlier by exposure to the CS+ flavor for independent groups. The CS+ exposure attenuated saccharin aversion learning if it occurred immediately before the saccharin conditioning trial but not if it occurred 1 h or more before conditioning. In Experiment 2, the saccharin conditioning trial was preceded 3 or 4.5 h earlier by a lithium injection. This proximal US preexposure injection was either unannounced (Li) or preceded by exposure to the CS+ (CS+Li) or the CS? (CS?Li) stimuli. The US preexposure attenuated saccharin aversion learning in all cases. However, the interference effect was less when the preexposure injection was expected (CS+Li) than when it was unexpected (CS?Li). This outcome could not be explained in terms of direct effects of the CS+ and CS? stimuli on the saccharin conditioning trial, and shows that the proximal US preexposure effect is a function of not only the drug dosage and preexposure interval, but also the anticipation of the drug pretreatment. 相似文献
11.
Three experiments investigated conditioning of the rabbit’s nictitating membrane response (NMR) in a second-order conditioning procedure which intermixed first-order trials (CS1-US) and second-order trials (CS2-CS1) from the outset of training. Experiment 1 provided a controlled demonstration that substantial levels of second-order conditioning can be obtained with the NMR preparation. Experiment 2 showed that the level of CR acquisition to CS2 was an inverse function of the CS2-CS1 interval over the values of 400, 800, and 2,400 msec. Experiment 3 found that CR acquisition to CS2 and CS1 in second-order conditioning varied in a parallel fashion across CS1-US intervals. Similarly, Experiment 3A found that the level of CR acquisition to the two components of a serial compound (CSA-CSB-US) varied in a parallel fashion as a function of the CSB-US interval. The results of the CS2-CS1 and CS1-US interval manipulations were all predictable from the known CS-US interval effects in NMR conditioning with a single CS. The present results are discussed with regard to their implications for accounts of serial compound conditioning and second-order conditioning. 相似文献
12.
赵路 《鞍山师范学院学报》2008,10(1):58-60
语码转换是一种有趣而又独特的社会语言现象。目前,有关语码转换的研究主要集中在两个方面：1.对语码转换概念的探索以及对这一语言现象的历时性研究;2.大量的关于语码转换的语用及句法结构特征的个案研究。本文探讨了语码转换的社会属性及其语用功能。同时,鉴于以往研究中人们对语码转换这一概念缺乏统一的认识,本文也试图为语码转换提出一个工作定义。 相似文献
13.
Sylvia Beyer 《Computer Science Education》2013,23(2-3):153-192
This study addresses why women are underrepresented in Computer Science (CS). Data from 1319 American first-year college students (872 female and 447 male) indicate that gender differences in computer self-efficacy, stereotypes, interests, values, interpersonal orientation, and personality exist. If students had had a positive experience in their first CS course, they had a stronger intention to take another CS course. A subset of 128 students (68 females and 60 males) took a CS course up to one year later. Students who were interested in CS, had high computer self-efficacy, were low in family orientation, low in conscientiousness, and low in openness to experiences were more likely to take CS courses. Furthermore, individuals who were highly conscientious and low in relational-interdependent self-construal earned the highest CS grades. Efforts to improve women’s representation in CS should bear these results in mind. 相似文献
14.
We used an appetitive sensory preconditioning procedure to investigate temporal integration in rats in two experiments. In
Phase 1, rats were presented with simultaneous compound trials on which a 10-sec conditioned stimulus (CS) X was embedded
within a 60-sec CS A. In Group Early, CS X occurred during the early portion of CS A, whereas in Group Late, CS X occurred
during the latter portion of CS A. In Phase 2, CS X was paired simultaneously with sucrose. On a subsequent test with CS A,
the rate of magazine entries peaked during the early portions of the stimulus in Group Early and during the latter portions
of the stimulus in Group Late (Experiments 1 and 2). Similar response peaks were not observed on tests with a control stimulus
that had been presented in compound with a stimulus that did not signal reward (Experiment 2). 相似文献
15.
Robert Deutsch 《Learning & behavior》1978,6(3):258-260
Previous studies on the effect of CS amount/duration on the conditioning of taste aversion have reported that animals having greater contact with the CS acquire greater aversion. These findings appear to contradict studies of CS preexposure, which show that greater contact with the CS results in less aversion. In the present research, the effect of CS amount was shown to depend on the CS-US interval. Thus, a 10-ml CS (0.15% saccharin) at 3- and 9-h CS-US intervals produced less aversion than a 1-ml CS, but there was no significant effect of CS amount at a 30-min interval. These results suggest a two-process interpretation of the delay gradient in conditioned taste aversion: one process (learned safety) is dominant at relatively long CS-US intervals, and a different process becomes dominant at short intervals. 相似文献
16.
Richard M. Wielkiewicz 《Learning & behavior》1979,7(2):246-250
Forty-eight albino rats were first exposed to randomly intermixed, noncontingent presentations of one pellet, six pellets, and water. For each of three groups, a CS+ was paired with one of the reinforcers, while the other two reinforcers and a CS? were presented alone. Then half the subjects experienced a six-pellet reward and half experienced a one-pellet reward for leverpresses during a light SD. Finally, on test trials, the CS+ or CS? was compounded with the light. Latencies on test trials indicated that responding for the one-pellet reward was significantly more disrupted by a CS+ for six pellets than by the CS+ for one pellet or the CS+ for water. Responding for the six-pellet reward was disrupted by the CS+ for one pellet somewhat more than by the CS+ for six pellets or water, but not significantly so. This pattern of results is partially consistent with an associative model of transfer and appears to contradict a motivational account of such effects. 相似文献
17.
18.
CS2-CS1-US autoshaping was given to hungry pigeons and evidence of CS2-CS1 association was sought. Pigeons pecked that key of a two-key compound CS2 located where the upcoming CS1 key light was to occur. Such CS2-CS1 association was: (1) quickly acquired, (2) quite durable, and (3) stronger with simultaneous than with successive discrimination tasks. 相似文献
19.
A national web-based survey was administered to 700 undergraduate computer science (CS) programs in the United States as part of a stratified random sample of 797 undergraduate CS programs. The 251 program responses (36% response rate) regarding social and professional issues are presented. This article describes the demographics of the respondents, presents results concerning whether programs teach social and professional issues, how social and professional issues are integrated, perceptions of CS faculty regarding the importance of social and professional issues, pedagogies used to teach social and professional issues, and what specific social and professional topics have been included in the CS curriculum. Additionally, we (a) provide suggestions for CS programs regarding the integration of social and professional issues into the CS curriculum, (b) suggest ways to encourage more social and professional coverage in CS programs, pedagogy, and (c) recommend what social and professional topics should be included in future CS curriculum reports. 相似文献
20.
Suppression of operant responding during a conditioned stimulus (CS) was studied in two procedures. In both procedures, operant leverpressing was maintained by a variable-interval 1-min food-delivery schedule, and insertion of a second lever served as the CS. In the first procedure, autoshaping, food followed each CS presentation irrespective of a subject’s behavior during the CS. In the second procedure, omission training, contact with the CS canceled the delivery of food scheduled for the end of that CS. In the first experiment, subjects were exposed to omission training followed by autoshaping; these procedures were reversed in the second experiment. In each experiment, the omission contingency resulted in fewer CS contacts and less suppression of operant responding during the CS than did autoshaping. These differences were more notable in subjects receiving the sequence autoshaping→omission training (Experiment 2). Direct observations in Experiment 2 revealed that, for subjects that were contacting the CS frequently when the omission contingency was introduced, reductions in signal contacts were accompanied by redistributions of behavior. The form of these redistributions depended upon behavior allocation at the time the omission contingency was imposed. 相似文献