A two-factor theory of stimulus-repetition effects

It is a well-documented finding that children respond more slowly to a stimulus that has been presented repeatedly just before test than to a novel stimulus. The effect, for which a two-factor theory has recently been proposed, did not occur in the only previous study of adults using a comparable procedure. Experiment 1 demonstrated the effect with adults. The previous negative finding may have been the result of too few repetitions of the stimulus. Experiment 2 provided additional support for the two-factor theory. The theory suggests that the effect is the net result of partially counteracting changes in two attentional processes. One process, the alertness elicited by a stimulus, is held to decrease as a result of repeated presentation of the stimulus, while the second process, encoding, is facilitated. The hypothesis tested in Experiment 2 was that the alertness decrement dissipates over a brief passage of time, while the facilitation of encoding does not. Subjects exposed to a repeatedly presented color were tested either immediately thereafter or after a 15-min or 30-min interval. As predicted, the observed effect shifted from one of flower response to one of faster response to the repeated stimulus as the delay interval increased.     

Habituation, response to novelty, and dishabituation in human infants: tests of a dual-process theory of visual attention

Two experiments were conducted to test a dual-process theory of infants' performance on visual habituation-dishabituation tasks. The findings demonstrate that (a) infant habituation functions are often nonmonotonic, with fixation increasing before the eventual response waning; (b) this initial increment in responding is related to stimulus "complexity"; (c) response to novelty is enhanced by increasing the "complexity" of the novelty-test stimulus; and (d) dishabituation, followed by decay, occurs for familiarized patterns when retested after the introduction of a "complex" stimulus, but not after introduction of a "simple" stimulus. Following P. Groves and R. Thompson (1970, Psychological Review, 77, 419-450) we propose that infant visual attention to repeated presentations of a stimulus involves two processes, habituation and sensitization.     

Saccade latency and warning signals: Stimulus onset,offset, and change as warning events

Two experiments investigated saccade latency to a peripheral target under various warning signal conditions. In Experiment I, the effects of warning stimulus onset, change, and two offset conditions were compared at warning intervals of 0, 100, 300, and 600 msec. Warning stimulus onset, change, and offset were all effective in reducing saccade latency as compared to a no-warning control condition, but warning stimulus offset resulted in shorter saccade latency than onset or change at all warning intervals. Experiment 2 compared onset and offset warning conditions at ?300-, ?250-, ?200-, ?150-, ?100-, ?50-, 0-, and 50-msec intervals. Responses following onset were slower than those following offset at the latter five intervals, while warning onset resulted in slower saccades than no-warning control conditions at ?150-, ?100-, and ?50-msec intervals. These results indicate that the onset of a visual warning signal can have an interfering effect on the programming or execution of a saccade.     

The interaction between alerting and executive control: Dissociating phasic arousal and temporal expectancy

In recent years, studies have revealed an interaction between two systems of attention—alerting and executive control. Specifically, warning cues increase the influence of cognitive conflict under certain conditions. One of the problems of interpreting this effect is that warning cues can trigger two processes simultaneously—a high arousal state and strategic temporal expectancy. The goal of the present study was to clarify which process underlies the increased congruency effects following a warning event. In two experiments, the influence of warning cues on flanker congruency was examined while controlling for the effects of temporal expectancy and arousal. Experiment 1 revealed a strong effect of warning cues on congruency, even when the warning cues were not temporally predictive. This effect was evident at two short cue-to-target intervals of 100 and 500 ms, but not following a 900-ms interval. Experiment 2 revealed that this effect was not altered even when the warning cues predicted with high certainty that the target would appear at long cue-to-target intervals (e.g., 900 ms). We suggest that the interaction between alerting and executive control reflects the involvement of a subcortical mechanism responsible for increasing arousal.     

Behavioral decrement following stimulus preexposure: effects of number of preexposures, presence of a second stimulus, and interstimulus interval in children and adults.

This article presents an analysis of the similarities between the stimulus familiarization effect and latent inhibition. Just as latent inhibition has been readily demonstrated in infrahumans, and only with considerable difficulty in adult humans, the experiments reported here obtained a significant interaction between the stimulus familiarity effect and age. Children exhibited increased reaction time to preexposed stimuli as opposed to nonpreexposed stimuli, but adults did not show this effect. In addition, a number of variables were shown to affect the amount of decrement. The decrement increased as a function of the number of preexposures and decreased with the addition of a second stimulus placed in a conditioning relationship to the to-be-tested stimulus during preexposure. However, an increased in the interstimulus interval was only marginally effective in increasing the inhibitory effects of preexposure. The data were discussed in relation to a conditioned attention explanation for these phenomena of behavioral decrement.     

女性对新异性事件加工的偏向:来自ERP的证据

采用修订后的oddball范式,结合ERP技术考察女性与男性在加工中性新异刺激时的差异。ERP结果表明,在早期已经出现新异性效应。在300-500ms内,新异刺激在男性和女性被试中都比标准刺激诱发了更大的LPC。在500-700ms内,新异刺激仅在女性被试中比标准刺激诱发更大的LPC,在男性被试中没有显著差异。这些结果表明男性和女性都对中性新异刺激表现出加工偏向,但是女性对其加工的时间比男性更长。这可能与女性容易对显著性(salient)的刺激进行沉思(rumination)相关。     

Probability effects on stimulus evaluation and response processes.

This study investigated the effects of probability information on response preparation and stimulus evaluation. Eight subjects responded with one hand to the target letter H and with the other to the target letter S. The target letter was surrounded by noise letters that were either the same as or different from the target letter. In 2 conditions, the targets were preceded by a warning stimulus unrelated to the target letter. In 2 other conditions, a warning letter predicted that the same letter or the opposite letter would appear as the imperative stimulus with .80 probability. Correct reaction times were faster and error rates were lower when imperative stimuli confirmed the predictions of the warning stimulus. Probability information affected (a) the preparation of motor responses during the foreperiod, (b) the development of expectancies for a particular target letter, and (c) a process sensitive to the identities of letter stimuli but not to their locations.     

The differential effects of brief exposures and surrounding contours on direct and indirect tilt illusions

Four experiments in which logarithmic intervals between 25 and 1600 ms were used for stimulus duration in tests for the tilt illusion are reported. It is demonstrated that the direct and the indirect tilt illusions both increase in magnitude inversely with length of stimulus presentation. The data suggest that whereas the direct effect peaks with a value of about +7 degrees at the shortest flash duration used (25 ms), peak indirect effects (of about +2 degrees) do not occur at this duration. In addition, whereas direct effects level out after 100 ms stimulus exposure times, to the usual magnitude obtained with long presentations (about +2 degrees), indirect effects reach their standard magnitude (-0.5 degrees to -1.0 degrees) later, at exposures of about 400 ms. Even at very short flash durations, a luminance square frame surrounding the illusion display reduces the indirect effect by two thirds of its magnitude but has no effect at all on the direct effect. It is suggested that direct effects arise early in visual processing, in area V1, where there are transient mechanisms and where corruption of orientation analysis by the inducing grating would occur prior to later, extrastriate, global analysis of the surrounding peripheral frame. Indirect effects, on the other hand, may arise later, along the sustained parvocellular colour-form pathway, where more global processing occurs and susceptibility to surrounding fields might be expected.     

重复知盲效应产生的机制——来自汉语叠词加工的证据

以汉语中的叠词为实验材料,对重复知盲产生机制的类型标记个体化理论和建构理论进行检验。采用RSVP研究范式,在两个实验中让178名被试口头报告列表中出现的所有汉字（全部报告）或列表中最后两个字（部分报告）。结果发现：（1）在呈现速率为128ms和198ms时,完全重复的汉字在全部报告和部分报告任务中均存在RB效应,但在部分报告任务下出现的RB相比全部报告任务的减少了,符合建构理论的假设。（2）在全部报告条件下,不仅重复刺激的正确报告率会降低,而且与重复刺激相关的非重复刺激的正确报告率也会降低。研究表明建构理论比类型标记个体化理论更能解释RB效应的产生机制。     

Asymmetry of generalization decrement in causal learning

Two experiments required volunteers to learn which of various “planes” caused high levels of pollution. Novel test items were then rated as causes of pollution. Items created by adding novel features were rated at the same level as that of the original training items but items created by removing features received reduced ratings. This asymmetry of generalization decrement was not predicted by a well-known configural model of stimulus representation (Pearce, 1987, 1994) but was predicted by a recently proposed model of stimulus representation, the replaced-elements model (Brandon, Vogel, & Wagner, 2000).     

Novelty as a reinforcer for position learning in children

The stimulus-familiarization-effect (SFE) paradigm, a reaction-time (RT) task based on a response to novelty procedure, was modified to assess response for novelty, i.e., a response-reinforcement sequence. Ninetysix kindergarten children were familiarized on one of two colored lights. Then Ss were confronted with a simple position discrimination task in which they could choose between two response buttons which produced either the previously familiarized light or a new (i.e., novel) light. Results showed that the choice response for the novel stimulus (NS) was facilitated by three variables: number of exposures to and duration per exposure of the familiar stimulus (FS), and degree of change provided by the NS relative to the FS. The parallel between the effective variables of this study and those which produce the SFE was noted, implicating an attention interpretation of the function of novelty as a reinforcer. The potential implications of attention for reinforcement theory and learning in general are discussed.     

The effect of warning interval on the electric phosphene and auditory thresholds

Using different warning signals and threshold stimuli, the thresholds, as determined by a method of limits, were found to rise monotonically as the interval between warning signal and threshold stimulus increased from I to 9 sec. It was found that the variability of the threshold did not increase as the threshold increased. Similar results were obtained for phosphene and auditory thresholds and with visual and auditory warnings; therefore the effect was considered to be central. Motokawa's finding of a minimum in the phosphene threshold 2 sec. after a flash of white light was not repeated. The rise in threshold was not obtained when the warning intervals were randomized and so seemed to depend on the use of fixed warning intervals. A model was developed relating threshold level to accuracy of anticipation of the end of the warning interval.     

Re-assessing causal accounts of learnt behavior in rats

Rats received either a common-cause (i.e., A→B, A→food) or a causal-chain training scenario (i.e., B→A, A→food) before their tendency to approach the food magazine during the presentation of B was assessed as a function of whether it was preceded by a potential alternative cause. Causal model theory predicts that the influence of an alternative cause should be restricted to the common-cause scenario. In Experiment 1, responding to B was reduced when it occurred after pressing a novel lever during the test phase. This effect was not influenced by the type of training scenario. In Experiment 2, rats were familiarized with the lever prior to test by training it as a potential cause of B. After this treatment, the lever now failed to influence test responding to B. In Experiment 3, rats given common-cause training responded more to B when it followed a cue that had previously been trained as a predictor of B, than when it followed another stimulus. This effect was not apparent in rats that received causal-chain training. This pattern of results is the opposite of that predicted by causal model theory. Thus, in three experiments, the presence of an alternative cause failed to influence test responding in manner consistent with causal model theory. These results undermine the application of causal model theory to rats, but are consistent with associative analyses.     

Asymmetrical effects of Pavlovian excitatory and inhibitory aversive transfer on Pavlovian appetitive responding and acquisition

Predictions of a theory of Pavlovian motivational transfer, which incorporates principles of both the theory of reciprocal inhibition and the Rescorla-Wagner model, were tested in several Pavlovian aversive to Pavlovian appetitive transfer tasks. As predicted, the presence of a signal for an aversive event, conditioned stimulus (AV CS+), reliably suppressed performance of appetitive conditioned responses (CRs) whether imposed during acquisition or on independently established responding. Acquisition of appetitive responding to a novel CS reinforced in compound with an AV CS+, however, was enhanced (“superconditioning”). This observation suggests that the effects of a discrepancy between expectation and actual outcome on a conditioning trial are influenced by the affective value of both the expectation and the reinforcer. These transfer effects were not symmetrical for an inhibitory aversive stimulus (AV CS?). An AV CS? did not enhance appetitive responding compared to a random control condition, nor did the AV CS? reduce (i.e., block) appetitive conditioning to a novel CS when appetitive reinforcement occurred in the presence of the AV CS?. Comparison of the two shock-exposed conditions with a naive control condition suggests that previous results that were apparently consistent with inhibitory aversive enhancement and blocking of appetitive conditioning may have been due to aversive context conditioning.     

Phasic alertness and the residual task-switching cost

Participants switched between two randomly ordered discrimination tasks and each trial began with the presentation of a task cue instructing which task to execute. The authors induced phasic alertness by presenting a salient uninformative stimulus after the task cue was provided, and at variable intervals before the target stimulus was presented (Experiments 1-3) or before the task cue (Experiment 4). When the alerting stimulus preceded the target stimulus or the task cue by an optimal interval, RT was faster, indicating an alert state and the task-switching cost was reduced. These results support the suggestion of De Jong (Acta Psychologica, 1999) that alertness improves the overcoming of retrieval competition through improved goal representation, but also show that the effect is specific to the residual task-switching cost.     

Age related changes in the effectiveness of name and visual codes in recognition memory

In the first of three studies college, third grade, and kindergarten Ss were able to determine that two stimuli presented 700 msec apart were the same more quickly if they were visually identical than if they shared the same name. If 3000 msec elapsed between stimulus presentations third grade and college Ss responded at the same rate in making both types of matches, whereas kindergarten Ss appeared to continue to respond more quickly in making visual matches. Study II was an unsuccessful attempt to replicate the kindergarten finding. A warning signal, presented 500 msec prior to the second stimulus, reduced RTs at both interstimulus intervals, but no significant differences in making visual and name matches occurred. In Study III first-graders, responding either with or without a warning signal, were found to respond like the older Ss in Study I. The warning signal again reduced RT at both intervals. The results suggest that Ss across a wide age range are able to use the visual properties of a stimulus for only a very brief period as the basis for making matching judgments.     

Learning the moves: the effect of familiarity and facial motion on person recognition across large changes in viewing format

Familiarity with a face or person can support recognition in tasks that require generalization to novel viewing contexts. Using naturalistic viewing conditions requiring recognition of people from face or whole body gait stimuli, we investigated the effects of familiarity, facial motion, and direction of learning/test transfer on person recognition. Participants were familiarized with previously unknown people from gait videos and were tested on faces (experiment 1a) or were familiarized with faces and were tested with gait videos (experiment 1b). Recognition was more accurate when learning from the face and testing with the gait videos, than when learning from the gait videos and testing with the face. The repetition of a single stimulus, either the face or gait, produced strong recognition gains across transfer conditions. Also, the presentation of moving faces resulted in better performance than that of static faces. In experiment 2, we investigated the role of facial motion further by testing recognition with static profile images. Motion provided no benefit for recognition, indicating that structure-from-motion is an unlikely source of the motion advantage found in the first set of experiments.     

Lexical competition and the acquisition of novel words

Three experiments examined the involvement of newly learnt words in lexical competition. Adult participants were familiarized with novel nonsense sequences that overlapped strongly with existing words (e.g. cathedruke, derived from cathedral) through repeated presentation in a phoneme-monitoring task. Experiment 1 looked at the immediate effects of exposure to these sequences, with participants showing familiarity with the form of the novel sequences in a two-alternative forced choice task. The effect of this exposure on lexical competition was examined by presenting the existing words (e.g. cathedral) in a lexical decision task. The immediate effect of the exposure was facilitatory, suggesting that the novel words had activated the representation of the closest real word rather than developing their own lexical representations. In Experiment 2, inhibitory lexical competition effects emerged over the course of 5 days for offset-diverging (e.g. cathedruke-cathedral) but not onset-diverging (e.g. yothedral-cathedral) novel words. Experiment 3 disentangled the roles of time and level-of-exposure in the lexicalization process and assessed the generality of the observed lexical inhibition using pause detection. A single, concentrated exposure session was used, which resulted in good recognition performance soon after. Lexicalization effects were absent immediately after exposure but emerged 1 week later, despite no intervening exposure to the novel items. These results suggest that integrating a novel word into the mental lexicon can be an extended process: phonological information is learnt swiftly, but full integration with existing items develops at a slower rate.     

The influence of stimulus incongruity on the familiarity effect in visual selection

A consistent finding in the literature concerning visual selection is that a stimulus exposed to S subsequently loses some of its potential to elicit looking responses. Studies examining the familiarity effect in visual selection have not systematically examined the influence on that effect of various stimulus characteristics possessed by the familiarized stimulus. The present experiments examined the relationship between the magnitude of the familiarity effect and the level of incongruity represented by the familiarized stimulus and found it to be increasing and monotonie. In addition, Experiment 3 examined the generality of reports that familiarized stimuli are “liked” less than their unfamiliarized counterparts. The ease of explaining the results of the experiments using an “affect change” model of the familiarity effect and an “inforjnation-conflict resolution” model of that effect are discussed.     

Contextual Fear after Signalled versus Unsignalled Shocks: Effect of Extent of Prior Experience with Context and Signal

In the first two experiments, rats were differentially familiarized with a discrete stimulus and/ or a context prior to receiving either shocks signalled by that stimulus or unsignalled shocks in that context. As indexed by freezing, in none of the pre-exposure conditions did the signalled-shock rats consistently acquire less contextual fear than the unsignalled-shock animals. Both pre-exposure to the stimulus and relatively short pre-exposure to the future conditioning context resulted in more contextual fear in the signalled-shock than in the unsignalled-shock subjects. In a third experiment, freezing in the target conditioning context was especially enhanced in rats that had been familiarized with a stimulus, conditioned with the stimulus as a signal for shock, and subsequently further conditioned to the stimulus in a different, non-target context. The level of freezing to the stimulus in a neutral test context was positively related to the level of freezing in the target conditioning context in all experiments. These results were discussed in terms of context-shock, stimulus-shock, and context-stimulus associations.