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1.
Three budgerigars were trained with operant techniques to discriminate examples of species-specific contact calls. Once the birds learned the discrimination among a large set of calls, they were tested with the calls altered in various ways. The birds’ performance on altered calls was compared with performance on normal calls. Results show that the birds could tolerate large spectral and temporal alterations in the calls with little or no decrement in performance. A comparison of the birds’ performance across conditions shows clear evidence of a redundancy in information contained in the calls. The birds were equally adept at discriminating among the calls when given only high-frequency information and when given only low-frequency information. The birds also performed just as well when presented with only the short beginning portions of the calls as they did when presented with somewhat longer portions near the end of the calls. This ability of budgerigars to discriminate among species-specific vocal signals that are highly distorted is reminiscent of the ability of humans to discriminate and recognize highly distorted speech sounds.  相似文献   

2.
The short-term memory for sounds of the bottlenosed dolphin was tested using symbolic, identity, and probe forms of the delayed matching-to-sample (DMS) task. The forms differed in the number (one or two) or nature (symbolic or identity matches of sample sounds) of postdelay test stimuli available as memory retrieval cues. Although symbolic DMS was difficult to learn, the final performance level was approximately equal to that for identity or probe DMS. On all tasks, the dolphin’s responses were above 80% correct through to delays of 90 sec and, in some cases, through to delays of 180 and 240 sec, the “limits” being governed mainly by the dolphin’s reluctance to continue being tested at long delays. Encoding of sample stimuli into their learned symbolic representation was hypothesized to have reduced symbolic DMS to a recognition memory task, resulting in the observed equivalence of performance with the other two recognition memory tasks. The probe DMS results, unlike those for identity or symbolic DMS, showed no significant proactive interference effects from samples of prior trials. Instead, proactive interference was traceable to the probe value of the prior trial. Overall, the auditory DMS data for the dolphin were functionally similar to results reported for monkeys tested on symbolic, identity, and probe visual DMS tasks.  相似文献   

3.
In the delayed matching of key location procedure, pigeons must remember the location of the sample key in order to choose correctly between two comparison keys. The deleterious effect of short intertrial intervals on key location matching found in previous studies suggested that pigeons’ short-term spatial memory is affected by proactive interference. However, because a reward expectancy mechanism may account for the intertriai interval effect, additional research aimed at demonstrating proactive interference was warranted. In Experiment 1, matching accuracy did not decline from early to late trials within a session, a finding inconsistent with a proactive interference effect. In Experiment 2, evidence suggestive of proactive interference was found: Matching was more accurate when the locations that served as distractors and as samples were chosen from different sets. However, this effect could have been due to differences in task difficulty, and the results of the two subsequent experiments provided no evidence of proactive interference. In Experiment 3, the distractor on Trialn was either the location that had served as the sample on Trialn ? 1 or one that had been a sample on earlier trials. Matching accuracy was not inferior on the former type of trial. In Experiment 4, the stimuli that served as samples and distractors were taken from sets containing 2, 3, 5, or 9 locations. Matching accuracy was no worse, actually slightly better, with smaller memory set sizes. Overall, these findings suggested that pigeons’ memory for spatial location may be immune to proactive interference. However, when, in Experiment 5, an intratrial manipulation was used, clear evidence of proactive interference was found: Matching accuracy was considerably lower when the sample was preceded by the distractor for that trial than when it was preceded by the sample or by nothing. Possible reasons why interference was produced by intratrial but not intertrial manipulations are discussed, as are implications of these data for models of pigeons’ short-term spatial memory.  相似文献   

4.
In Experiment 1, short-term memory for lists of visual stimuli was studied in four squirrel monkeys (Saimiri sciureus). A delayed-matching procedure was used in which a subject was presented with lists containing one, three, or six stimulus patterns, and memory for serial positions was probed by requiring the subject to choose between a list item and a nonlist item. The rate of item presentation was varied, as was the delay between the final item on a list and the retention test. In Experiment 2, the same procedures were used to compare recognition memory in four monkeys and four humans. Although differences in the levels and shapes of the serial-position curves appeared between species, both monkeys and humans showed primacy and recency effects. The presentation time of stimuli had a negligible effect on performance in both monkeys and humans, whereas delay significantly affected human retention but not monkey retention.  相似文献   

5.
While some difficult learning conditions can improve learning, the findings regarding the contribution to learning of disfluent, hard-to-read text materials have been inconsistent. We identified test delay and disfluency manipulations as factors potentially contributing to these discrepancies. We tested students' immediate and delayed memory performance (2 weeks later) on a course text that was presented between-subjects (N = 134) either as perceptually disfluent with a hard-to-read-font, as lexically disfluent with 20% scrambled letters, or in its original format. By distinguishing between short-term and long-term learning, our expectations were supported; an illegible font reduced forgetting, thereby producing delayed memory benefits. We also tested whether lexical disfluency would have similar memory effects as perceptual disfluency, as the meta-cognitive perspective suggests, or whether different disfluency manipulations would have different memory effects, as ideas from a contextualized framework on desirable difficulties suggests. The findings supported the latter. The results are discussed regarding the generalizability of the disfluency effects and the implications for when disfluency is desirable.  相似文献   

6.
Two experimental paradigms are presented aimed at determining the retention of auditory and visual information over brief delay intervals. First, a conditional delayed matching-to-sample procedure was used in which rats were required to symbolically match the modality of the sample stimulus with one of two comparison stimuli. In the second experiment, subjects were trained and tested using a Konorski-type procedure. Despite the conceptual and procedural differences between the two procedures, subjects in both experiments showed steeper forgetting functions for visual events than for auditory events, while performance levels at 0-sec delay intervals were equivalent for both stimuli. These results, when taken together with related research conducted with pigeons, suggest that content of memory may have important influences on the short-term retention abilities of animal subjects.  相似文献   

7.
揭示学习与记忆的神经机制已成为认知科学领域的一个重要研究方向.鸣禽的鸣啭表现出一种复杂的学习过程.鸣禽学习鸣啭的过程可以分为两个阶段.在感觉学习期,幼鸟必须听到成鸟的鸣啭,并形成鸣啭模板记忆;在感觉运动学习期,鸣禽通过听觉反馈与模板匹配逐步建立稳定的鸣啭.LTP(long term potentiation)是一种研究学习记忆突触基础的主要模型,其代表突触功能的可塑性.本文对近年来鸣禽神经系统可塑性及习鸣研究进展进行综述.  相似文献   

8.
A bottlenosed dolphin (Tursiops truncatus) with good underwater and aerial visual acuity was tested in visual matching-to-sample (MTS) paradigms. Attempts to train visual identity MTS directly, using two simple two-dimensional patterns as sample stimuli and as alternatives (comparison stimuli), met with little success, in keeping with previously observed difficulties of this auditory-specialized species for learning complex tasks utilizing simple visual materials. Pairing of each visual sample with a unique sound, to produce a compound auditory-visual sample, while retaining the two visual alternatives, resulted in the dolphin’s learning both auditory-visual symbolic matching and visual-visual identity matching. At 0-sec delay, performance with the auditory element of the sample alone was equivalent (76%) to performance with the visual element alone; performance with the compound was distinctly better (95%–98% correct). Testing with longer delays using the visual element alone resulted in successful matching through to a maximum delay of 34 sec. These results provided the first demonstration of delayed MTS in a dolphin using visual materials, and complemented other data showing the ready capability of this species for delayedauditory MTS. It appeared that the dolphin solved the visual MTS task by forming auditory codes to represent the visual materials, and that these auditory codes were eventually replaced with purely visual codes.  相似文献   

9.
Interference in auditory short-term memory in the bottlenosed dolphin,Tursiops truncatus (Montagu), was studied using a delayed matching-to-sample task. At each trial, one of two sample sounds, chosen randomly, was projected underwater for 4 sec and then, after a variable delay interval, both sounds were presented. A response to the sound matching the initial sample was reinforced. Correct matching was significantly reduced following short intervals between trials in combination with long delays after the sample (proactive interference), or when a near continuous irrelevant sound was inserted into the delay interval (retroactive interference). There was rapid habituation to interference if the irrelevant sound was short in duration relative to the delay interval. For both proactive and retroactive interference, the errors were predominantly responses to the sample sound appropriate to the prior trial rather than to the current trial, indicating that memory for the relative recency of events (temporal memory) was degraded by interference. When interference was deleted or minimized, temporal memory remained nearly perfect over 30-sec delay intervals, the longest tested. The importance of distinguishing between temporal memory and nontemporal, or event, memory in different forms of the delayed matching task was emphasized.  相似文献   

10.
This study investigates the relationship between working memory and language in young children growing up in a multilingual environment. The aim is to explore whether mechanisms of short-term storage and cognitive control hold similar relations to emerging language skills and to investigate if potential links are mediated by related cognitive abilities. A sample of 119 Luxembourgish 6-year-olds completed several assessments of working memory (complex and simple span), native and foreign vocabulary, syntax, reading, rhyme awareness, and fluid intelligence. Results showed that short-term storage and cognitive control manifested differential links with developing language abilities: Whereas verbal short-term storage was specifically linked to vocabulary; cognitive control manifested unique and robust links with syntax and early reading development. The study suggests that in young children the working memory system is composed of separate but interacting components corresponding to short-term storage and cognitive control that can be distinguished by the roles they play in supporting language acquisition.  相似文献   

11.
Young adult subjects were trained in a discrimination involving three pure tones varying in pitch, with two positive stimuli and a negative stimulus located midway between the two. Subjects in the control conditions were trained only with the two positive stimuli. Generalization gradients were bimodal in all cases, but for the control subjects, the modes were at the positive stimulus values, while postdiscrimination gradients were displaced away from the negative stimulus toward the extremes of the continuum. Since, with this procedure, the training and test adaptation levels were the same, the observed displacements are difficult to explain in terms of an adaptation-level account of peak shifts. The observed shifts are more consistent with the conditioning-extinction model which assumes interactions between inhibitory and excitatory gradients. However, overall response rates did not reflect the action of summation processes.  相似文献   

12.
According to the mixed memory model (Penney, Gibbon, & Meck, Journal of Experimental Psychology: Human Perception and Performance, 26, 1770–1787, 2000), different clock rates for stimuli with different nontemporal properties must be stored within a single reference memory distribution in order to detect a difference between the clock rates of the different signals. In Experiment 1, pigeons were trained in a between-subjects design to discriminate empty intervals (bound by two 1-s visual markers) and filled intervals (a continuous visual signal). The intervals were signaled by different visual stimuli, and they required responses to different sets of comparison stimuli. Empty intervals were judged as being longer than filled intervals. The difference between the point of subjective equality (PSE) for the empty intervals and the PSE for the filled intervals increased proportionally as the magnitudes of the anchor duration pairs were increased from 2 and 8 s to 4 and 16 s. In Experiment 2, the pigeons were trained to discriminate intervals signaled by the absence of houselight illumination (Group Empty) or the presence of houselight illumination (Group Filled). The psychophysical timing functions for these intervals were identical to each other. The results of Experiment 1 indicate that memory mixing is not necessary for detecting a timing difference between empty and filled intervals in pigeons. The results of Experiment 2 suggest that the nature of the stimuli that signal the empty and filled intervals impacts how pigeons judge the durations of empty and filled intervals.  相似文献   

13.
To begin an investigation of the cellular processes that underlie long-term memory in the nematodeCaenorhabditis elegans, it is first necessary to determine thatC. elegans is capable of retention over 24 h, and to investigate the factors that may influence the expression of long-term memory. In the present study, the effects of stimuli number, interstimulus interval (ISI), and training procedure on long-term retention of habituation were tested inC. elegans. At a long (60-sec) ISI, distributed training sessions produced long-term habituation retained for 24 h, whereas massed training sessions or training with few stimuli did not. When training was performed at a short (10-sec) ISI, long-term habituation was not detectable with testing at either a 10- or a 60-sec ISI. The long-term habituation observed after distributed training sessions at a 60-sec ISI was consistently expressed when the training procedures were varied. Thus it is clear thatC. elegans can reliably express long-term retention for distributed training sessions at a 60-sec ISI, making the system a candidate for further investigations into the cellular processes supporting memory.  相似文献   

14.
The delayed matching-to-sample (DMTS) task was used in three experiments to investigate how pigeons code information about sample stimuli. In all experiments, each trial consisted of a signaled presentation of a sample stimulus for a fixed duration followed, after some delay, by the presentation of three comparison stimuli. After incorrect first choices, the bird was allowed a second choice between the remaining two stimuli. It was found, in Experiment 1, that the probability of a second choice error declined with increasing sample duration. This result is consistent with a gradual short-term memory encoding process but not with a simple two-state all-or-none process. In the second experiment, it was found that the distribution of first-choice errors was affected by the particular sample occurring on a trial. This result is inconsistent with a two-stage discrete state memory/attention model based on the assumption that encoding of the sample and attention to the comparison stimuli are both independent all-or-none processes. The third experiment involved symbolic DMTS, in which the sample stimuli varied along a dimension different from that along which the comparison stimuli varied. With increasing delay between sample and comparison stimulus presentations, the pigeons were more likely to confuse test stimuli than to confuse sample stimuli. The results of these experiments lead to the conclusion that pigeon DMTS performance depends on a gradual encoding process in which a representation isomorphic with the test stimuli is generated and maintained.  相似文献   

15.
The monkey’s capacity to extract tonal pattern from a sequence of tones was assessed in four subjects that had the benefit of substantial past experience in discriminating, matching, and remembering acoustic stimuli. In Experiment 1, the monkeys failed to transfer their well-established matching behavior to the matching of two structured sequences of tones that differed primarily in tonal pattern, indicating that for them tonal pattern was not a salient feature of the acoustic stimuli. Experiment 2 was an attempt to encourage tonal pattern perception by employing, within a discrimination paradigm, very simple tonal patterns and multiple exemplars of the positive and negative patterns; the transfer design, borrowed from Hulse and Cynx (1985), was a powerful one for revealing tonal pattern perception. Verifying earlier results from our laboratory, there was little in the monkeys’ transfer performance to indicate that they had extracted tonal pattern from the acoustic stimuli. Major discriminative control seemed to be vested in the first tone of each exemplar. This apparent cognitive limitation may be rather general among animals, perhaps reflecting an intimate connection between the capacity for tonal pattern perception and that for acoustically based language.  相似文献   

16.
Based on several recent demonstrations of a directed forgetting effect in pigeons, three experiments were carried out in an attempt to demonstrate directed forgetting in three squirrel monkeys. During initial training with a delayed matching-to-sample procedure, retention tests were always given for sample stimuli followed by remember cues (R-cues) and were always omitted for sample stimuli followed by forget cues (F-cues). Retention of F-cued items was tested on probe trials after initial training. The first two experiments examined the effects of R- and F-cues on memory for slide-projected pictures, with different pictures used on each trial of a session. In Experiment 1, a complex design was used in which one or two sample pictures were presented on each trial; when two pictures were presented, both could be R-cued or F-cued, or one could be R-cued and the other F-cued. A simpler design was used in Experiment 2, with only single pictures presented as sample stimuli and half the trials within a session R-cued and the other half F-cued. In both of these experiments, no differential retention of R- and F-cued stimuli was found, even at a retention interval as long as 16 sec. In Experiment 3, a series of studies was performed to test for directed forgetting when only two sample stimuli were used repeatedly throughout training and testing. With two pictures as sample stimuli, clear evidence of directed forgetting was found in Experiment 3b. It is suggested that the directed forgetting effect may arise only when a small set of sample stimuli is used.  相似文献   

17.
Spontaneous alternating behavior (SAB), the tendency of an organism to successively turn left and right in a maze, is a standard metric of short-term memory in developmental and pyschopharmacological studies. Although SAB is perhaps the most phylogenetically widespread behavior in motile lifeforms, conflicting data on SAB exist for several sets of closely related taxa. For example, previous studies provide contradictory evidence concerning the existence of spontaneous alternation behavior in the protozoanParamecium. However, these studies tested different species, using very different experimental designs. Using a single, factorial design for both previously tested species,P. multimicronucleatum andP. caudatum, we found that, in fact, the two species do not differ in their alternation behavior; specifically, they alternate in mazes with short tracks, but not in mazes with long tracks. These results are in accord with alternation studies on other taxa, and they fully resolve the apparent contradictions in the earlier studies onParamecium. They also indicate that caution should be used in interpreting variable results across species tested with different experimental designs and suggest that, in at least some taxa, SAB may not be strictly dependent on the use of short-term memory.  相似文献   

18.
Two experiments evaluating the effects of external stimuli on attack and biting in rats elicited by electric tailshock are reported. In the first experiment, stimuli presented to four groups of test subjects consisted of a stimulus animal, a stimulus animal plus taped vocalizations of a rat experiencing shock, an inanimate object, and an inanimate object plus taped vocalizations. Subjects in a fifth (control) group were tested in the absence of these stimuli. The presence of another animal in the test situation significantly increased the amount of target-directed responding. A decrease in responding, rather than increase, was shown by the subjects tested under the stimulus-object plus taped-vocalization conditions. Experiment 2 investigated the salient features of the stimulus animal and found a combination of both olfactory and visual cues to be most effective in eliciting target-directed responding. These studies indicate that the amount of target-directed attack and biting shown in this situation may be related causally to the type of sensory input received by the test animal.  相似文献   

19.
Separate groups of pigeons were trained to perform symbolic delayed matching to sample with auditory and visual sample stimuli. For animals in the auditory group, ambient tones that varied in frequency served as sample stimuli; for animals in the visual group, ambient red and green lights served as sample stimuli. In both cases, the sample stimuli were mapped onto the yellow and blue comparison stimuli presented on left and right pecking keys. In Experiments 1 and 2, it was found that visual and auditory delayed matching were affected in the same ways by several temporal variables: delay, length of exposure to the sample stimulus, and intertrial interval. In Experiments 3, 4A, and 4B, a houselight presented during the delay interval strongly interfered with retention in both visual and auditory groups, but white noise presented during the delay had little effect in either group. These results seem to be more in line with a prospective memory model, in which visual and auditory sample stimuli are coded into the same instructional memories, than with a model based on concepts of retrospective memory and modality specificity.  相似文献   

20.
The present study explores the relationship between sentence recall and reading and language skills in a group of 7–11-year-old children with learning difficulties. While recent studies have found that performance on sentence recall tasks plays a role in learning, it is possible that this contribution is a reflection of shared resources with working memory. In order to investigate whether sentence recall was uniquely associated with reading and language skills, differences associated with IQ and working memory capacity were statistically controlled. A sample of 72 children was tested on measures of verbal complex memory, verbal short-term memory, sentence recall, expressive vocabulary, verbal and performance IQ, reading and language skills. Both sentence recall and verbal complex memory shared unique links with reading skill, and sentence recall was uniquely associated with language skills. This finding indicates that resources in long-term memory also play an important diagnostic role in reading and language abilities. The implications for educational practice are discussed.  相似文献   

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