Probing attentional modulation of contextual cueing

The repetition of spatial layout implicitly facilitates visual search (contextual cueing effect; Chun & Jiang, 1998). Although a substantial number of studies have explored the mechanism underlying the contextual cueing effect, the manner in which contextual information guides spatial attention to a target location during a visual search remains unclear. We investigated the nature of attentional modulation by contextual cueing, using a hybrid paradigm of a visual search task and a probe dot detection task. In the case of a repeated spatial layout, detection of a probe dot was facilitated at a search target location and was inhibited at distractor locations relative to nonrepeated spatial layouts. Furthermore, these facilitatory and inhibitory effects possessed different learning properties across epochs (Experiment 1) and different time courses within a trial (Experiment 2). These results suggest that contextual cueing modulates attentional processing via both facilitation to the location of “to-be-attended” stimuli and inhibition to the locations of “to-be-ignored” stimuli.     

空间工作记忆负载对真实场景情境提示效应的影响

重复的画面布局能够促进观察者对目标项的搜索 (情境提示效应)。本研究采用双任务范式,分别在视觉搜索任务的学习阶段 (实验2a) 和测验阶段 (实验2b) 加入空间工作记忆任务, 并与单任务基线 (实验1)进行比较, 考察空间工作记忆负载对真实场景搜索中情境线索学习和情境提示效应表达的影响。结果发现: 空间负载会增大学习阶段的情境提示效应量, 同时削弱测验阶段的情境提示效应量, 而不影响情境线索的外显提取。由此可见, 真实场景中情境线索的学习和提示效应的表达均会受到有限的工作记忆资源的影响, 但情境线索提取的外显性不变。     

Selective attention in the speeded classification and comparison of multidimensional stimuli

Selective attention was studied when subjects were required to make either speeded classifications of single stimuli or comparisons of pairs of multidimensional stimuli. Experiment 1 established that subjects were able to attend selectively to form when the irrelevant dimension of size or shading varied in a speeded-classification (card-sorting) task. Experiment 2 confirmed this finding in a discrete-trials task. However, subjects werenot able to filter out irrelevant dimensional disparity in a comparably designed simultaneous-comparison (i.e., “same”-“different”) task. Mean “same” reaction time increased monotonically with increases in disparity between the two stimuli on the irrelevant dimension. Experiment 3 also revealed a monotonie increase in “same” RT as a function of irrelevant disparity in a successive-comparison task. These results were discussed in terms of a normalization model proposed by Dixon and Just (1978) in which it is assumed that a subject equates the two stimuli on the irrelevant dimension before deciding that they are the same along the relevant dimension. It was concluded that: (1) although subjects can efficiently filter out irrelevant disparity in a speeded-classification task, interference due to irrelevant disparity is obtained in the comparison tasks, (2) a common process such as normalization does not necessarily underlie performance in the speeded-classification and comparison tasks, (3) the ability to attend selectively to a stimulus dimension may be task determined as well as stimulus determined, and (4) contrary to the Dixon and Just proposal, normalization of irrelevant disparity occurs in a comparison task, even when the relevant dimension is represented as a separate encoding feature.     

Influence of stimulus symmetry and complexity upon haptic scanning strategies during detection,learning, and recognition tasks

Two experiments were conducted to investigate the perceptual processes involved in haptic exploration of randomly generated shapes. Experiment 1 required subjects to detect the symmetrical or asymmetrical characteristics of individually presented plastic shapes. The shapes also varied in complexity as measured by the number of sides. Experiment 2 involved learning a set of shapes and then attempting to recognize these “old” shapes when presented together with a series of “new” shapes. In both experiments, reaction time was investigated as a function of stimulus complexity and task requirements. Furthermore, it was observed that an initial orienting response was used to direct the subjects to adopt specific scanning strategies when examining asymmetrical or symmetrical shapes. The influences of stimulus properties and task requirements upon haptic encoding processes are discussed.     

Speech segmentation by statistical learning is supported by domain-general processes within working memory

The purpose of this study was to examine the extent to which working memory resources are recruited during statistical learning (SL). Participants were asked to identify novel words in an artificial speech stream where the transitional probabilities between syllables provided the only segmentation cue. Experiments 1 and 2 demonstrated that segmentation performance improved when the speech rate was slowed down, suggesting that SL is supported by some form of active processing or maintenance mechanism that operates more effectively under slower presentation rates. In Experiment 3 we investigated the nature of this mechanism by asking participants to perform a two-back task while listening to the speech stream. Half of the participants performed a two-back rhyme task designed to engage phonological processing, whereas the other half performed a comparable two-back task on un-nameable visual shapes. It was hypothesized that if SL is dependent only upon domain-specific processes (i.e., phonological rehearsal), the rhyme task should impair speech segmentation performance more than the shape task. However, the two loads were equally disruptive to learning, as they both eradicated the benefit provided by the slow rate. These results suggest that SL is supported by working-memory processes that rely on domain-general resources.     

Matching patterns vs matching digits: The effect of memory dependence and complexity on “same”-“different” reaction times

Two experiments are reported in which “same”-“different” reaction times (RTs) were collected to pairs of stimuli. In Experiment 1 stimuli were matrix patterns, and in Experiment 2 stimuli were digits. In both experiments, the pairs were presented simultaneously (discrimination task) and successively (memory task) for a set of nine simple and a set of nine complex stimuli. The following results were obtained: discrimination RTs were longer than memory RTs; RTs to complex stimuli were longer than RTs to simple stimuli; “same” RTs were faster than “different” RTs across all conditions except simple pattern discrimination, for which “different” RTs were faster than “same” RTs; and discrimination RTs for complex patterns were longer than would be predicted from the other conditions. Some evidence was obtained that the form of encoding for both patterns and digits in the memory task was visual. These results are discussed in terms of encoding and comparison strategies.     

Adaptive memory: Animacy effects persist in paired-associate learning

Recent evidence suggests that animate stimuli are remembered better than matched inanimate stimuli. Two experiments tested whether this animacy effect persists in paired-associate learning of foreign words. Experiment 1 randomly paired Swahili words with matched animate and inanimate English words. Participants were told simply to learn the English “translations” for a later test. Replicating earlier findings using free recall, a strong animacy advantage was found in this cued-recall task. Concerned that the effect might be due to enhanced accessibility of the individual responses (e.g., animates represent a more accessible category), Experiment 2 selected animate and inanimate English words from two more constrained categories (four-legged animals and furniture). Once again, an advantage was found for pairs using animate targets. These results argue against organisational accounts of the animacy effect and potentially have implications for foreign language vocabulary learning.     

Mental rotation is not easily cognitively penetrable

When participants take part in mental imagery experiments, are they using their “tacit knowledge” of perception to mimic what they believe should occur in the corresponding perceptual task? Two experiments were conducted to examine whether such an account can be applied to mental imagery in general. These experiments both examined tasks that required participants to “mentally rotate” stimuli. In Experiment 1, instructions led participants to believe that they could reorient shapes in one step or avoid reorienting the shapes altogether. Regardless of instruction type, response times increased linearly with increasing rotation angles. In Experiment 2, participants first observed novel objects rotating at different speeds, and then performed a mental rotation task with those objects. The speed of perceptually demonstrated rotation did not affect the speed of mental rotation. We argue that tacit knowledge cannot explain mental imagery results in general, and that in particular the mental rotation effect reflects the nature of the underlying internal representation and processes that transform it, rather than participants’ pre-existing knowledge.     

Selective impairment of masked priming in dual-task performance

This study investigated the impact of divided attention on masked priming. In a dual-task setting, two tasks had to be carried out in close temporal succession: a tone discrimination task and a masked priming task. The order of the tasks was varied between experiments, and attention was always allocated to the first task—that is, the first task was prioritized. The priming task was the second (nonprioritized) task in Experiment 1 and the first (prioritized) task in Experiment 2. In both experiments, “novel” prime stimuli associated with semantic processing were essentially ineffective. However, there was intact priming by another type of prime stimuli associated with response priming. Experiment 3 showed that all these prime stimuli can reveal significant priming effects during a task-switching paradigm in which both tasks were performed consecutively. We conclude that dual-task specific interference processes (e.g., the simultaneous coordination of multiple stimulus–response rules) selectively impair priming that is assumed to rely on semantic processing.     

Association learning and visual discrimination

The effect of learned stimulus associations on visual discrimination was measured in four experiments. The stimuli were visual shapes which had been scaled for similarity. Two shapes were selected as discriminanda, and each S was pretested and posttested for discrimination of these briefly presented simultaneous pairs of “same” and “different” shapes. During the training, each discriminandum was paired with another simultaneously presented associated shape on a paired-associate response-learning task. The two associated shapes were very similar, intermediate in similarity, or very dissimilar. There was more improvement in posttest discrimination following training with dissimilar associates. We conclude that learned stimulus associations affect visual discrimination.     

Collaboration and prospective memory: comparing nominal and collaborative group performance in strangers and couples

To perform prospective memory (PM) tasks in day-to-day life, we often enlist the help of others. Yet the effects of collaboration on PM are largely unknown. Adopting the methodology of the “collaborative recall paradigm”, we tested whether stranger dyads (Experiment 1) and intimate couples (Experiment 2) would perform better on a “Virtual Week” task when working together or each working separately. In Experiment 1, we found evidence of collaborative inhibition: collaborating strangers did not perform to their pooled individual potential, although the effect was modulated by PM task difficulty. We also found that the overall collaborative inhibition effect was attributable to both the retrospective and prospective components of PM. In Experiment 2 however, there was no collaborative inhibition: there was no significant difference in performance between couples working together or separately. Our findings suggest potential costs of collaboration to PM. Intimate relationships may reduce the usual costs of collaboration, with implications for intervention training programmes and for populations who most need PM support.     

Human preferences are biased towards associative information

There is ample evidence that the brain generates predictions that help interpret sensory input. To build such predictions the brain capitalizes upon learned statistical regularities and associations (e.g., “A” is followed by “B”; “C” appears together with “D”). The centrality of predictions to mental activities gave rise to the hypothesis that associative information with predictive value is perceived as intrinsically valuable. Such value would ensure that this information is proactively searched for, thereby promoting certainty and stability in our environment. We therefore tested here whether, all else being equal, participants would prefer stimuli that contained more rather than less associative information. In Experiments 1 and 2 we used novel, meaningless visual shapes and showed that participants preferred associative shapes over shapes that had not been associated with other shapes during training. In Experiment 3 we used pictures of real-world objects and again demonstrated a preference for stimuli that elicit stronger associations. These results support our proposal that predictive information is affectively tagged, and enhance our understanding of the formation of everyday preferences.     

The role of convexity in perception of symmetry and in visual short-term memory

Visual perception of shape is affected by coding of local convexities and concavities. For instance, a recent study reported that deviations from symmetry carried by convexities were easier to detect than deviations carried by concavities. We removed some confounds and extended this work from a detection of reflection of a contour (i.e., bilateral symmetry), to a detection of repetition of a contour (i.e., translational symmetry). We tested whether any convexity advantage is specific to bilateral symmetry in a two-interval (Experiment 1) and a single-interval (Experiment 2) detection task. In both, we found a convexity advantage only for repetition. When we removed the need to choose which region of the contour to monitor (Experiment 3) the effect disappeared. In a second series of studies, we again used shapes with multiple convex or concave features. Participants performed a change detection task in which only one of the features could change. We did not find any evidence that convexities are special in visual short-term memory, when the to-be-remembered features only changed shape (Experiment 4), when they changed shape and changed from concave to convex and vice versa (Experiment 5), or when these conditions were mixed (Experiment 6). We did find a small advantage for coding convexity as well as concavity over an isolated (and thus ambiguous) contour. The latter is consistent with the known effect of closure on processing of shape. We conclude that convexity plays a role in many perceptual tasks but that it does not have a basic encoding advantage over concavity.     

Making Probabilistic Relational Categories Learnable

Theories of relational concept acquisition (e.g., schema induction) based on structured intersection discovery predict that relational concepts with a probabilistic (i.e., family resemblance) structure ought to be extremely difficult to learn. We report four experiments testing this prediction by investigating conditions hypothesized to facilitate the learning of such categories. Experiment 1 showed that changing the task from a category‐learning task to choosing the “winning” object in each stimulus greatly facilitated participants' ability to learn probabilistic relational categories. Experiments 2 and 3 further investigated the mechanisms underlying this “who's winning” effect. Experiment 4 replicated and generalized the “who's winning” effect with more natural stimuli. Together, our findings suggest that people learn relational concepts by a process of intersection discovery akin to schema induction, and that any task that encourages people to discover a higher order relation that remains invariant over members of a category will facilitate the learning of putatively probabilistic relational concepts.     

Investigating the Role of Instructional Focus in Incidental Pattern Learning

The authors used a novel dual-component training procedure that combined a serial reaction time task and an artificial grammar learning task to investigate the role of instructional focus in incidental pattern learning. In Experiment 1, participants either memorized letter strings as a primary task and reacted to the stimuli locations as a secondary task or vice versa. In Experiment 2, participants were given the same dual-component stimuli but performed only one of the two training tasks. Instructional focus affected the amount of learning and the likelihood of acquiring explicit knowledge of the underlying pattern. However, the effect of instructional focus varied for the different types of stimuli. These results are discussed in terms of the role of focused attention in incidental learning.     

Pavlovian to instrumental transfer of control in a human learning task

Pavlovian learning tasks have been widely used as tools to understand basic cognitive and emotional processes in humans. The present studies investigated one particular task, Pavlovian-to-instrumental transfer (PIT), with human participants in an effort to examine potential cognitive and emotional effects of Pavlovian cues upon instrumentally trained performance. In two experiments, subjects first learned two separate instrumental response-outcome relationships (i.e., R1-O1 and R2-O2) and then were exposed to various stimulus-outcome relationships (i.e., S1-O1, S2-O2, S3-O3, and S4-) before the effects of the Pavlovian stimuli on instrumental responding were assessed during a non-reinforced test. In Experiment 1, instrumental responding was established using a positive-reinforcement procedure, whereas in Experiment 2, a quasi-avoidance learning task was used. In both cases, the Pavlovian stimuli exerted selective control over instrumental responding, whereby S1 and S2 selectively elevated the instrumental response with which it shared an outcome. In addition, in Experiment 2, S3 exerted a nonselective transfer of control effect, whereby both responses were elevated over baseline levels. These data identify two ways, one specific and one general, in which Pavlovian processes can exert control over instrumental responding in human learning paradigms, suggesting that this method may serve as a useful tool in the study of basic cognitive and emotional processes in human learning.     

Tasks determine what is learned in visual statistical learning

Visual statistical learning (VSL), the unsupervised learning of statistical contingencies across time and space, may play a key role in efficient and predictive encoding of the perceptual world. How VSL capabilities vary as a function of ongoing task demands is still poorly understood. VSL is modulated by selective attention and faces interference from some secondary tasks, but there is little evidence that the types of contingencies learned in VSL are sensitive to task demands. We found a powerful effect of task on what is learned in VSL. Participants first completed a visual familiarization task requiring judgments of face gender (female/male) or scene location (interior/exterior). Statistical regularities were embedded between stimulus pairs. During a surprise recognition phase, participants showed less recognition for pairs that had required a change in response key (e.g., female followed by male) or task (e.g., female followed by indoor) during familiarization. When familiarization required detection of “flicker” or “jiggle” events unrelated to image content, there was weaker, but uniform, VSL across pair types. These results suggest that simple task manipulations play a strong role in modulating the distribution of learning over different pair combinations. Such variations may arise from task and response conflict or because the manner in which images are processed is altered.     

When people’s judgments of learning (JOLs) are extremely accurate at predicting subsequent recall: the “Displaced-JOL effect”

Judgments of learning (JOL) made after a delay more accurately predict subsequent recall than JOLs made immediately after learning. One explanation is that delayed JOLs involve retrieving information about the target item from secondary memory, whereas immediate JOLs involve retrieval from primary memory. One view of working memory claims that information in primary memory is displaced to secondary memory when attention is shifted to a secondary task. Thus, immediate JOLs might be as accurate as delayed JOLs if an intervening task displaces the target item from primary memory, requiring retrieval from secondary memory, prior to making the JOL. In four experiments, participants saw related word-pairs and made JOLs predicting later recall of the item. In Experiment 1, delayed JOLs were more accurate than JOLs made shortly after learning, regardless of whether a secondary task intervened between learning and JOL. In Experiments 2–4, the secondary task demands increased and JOLs made shortly after learning with an intervening task were just as accurate as delayed JOLs, and both were more accurate than immediate JOLs with no intervening task (Experiment 4). These results are consistent with a retrieval-based account of JOLs, and demonstrate that the “delayed-JOL effect” can be obtained without a long delay.     

Differential effects of familiarity on judgments of sameness and difference

Ss indicated whether pairs of simultaneously presented objects were “same” or “different.” In Experiments 1, 2, and 3 the stimuli were pairs of letters, and familiarity was manipulated by showing the letters in either an upright or an upside-down orientation. In Experiments 4 and 5 the stimuli were pairs of trigrams, and familiarity was manipulated either by rotation or by selection according to rated meaningfulness. Analysis of reaction times indicated that familiar pairs were responded to more quickly than were unfamiliar pairs; however, this was true only for “same” judgments, not for “different” judgments. In addition, Experiment 3 indicated that familiarity influenced discrimination accuracy under conditions of tachistoscopic exposure. Finally, in Experiment 6 an effort was made to disentangle the effects of meaningfulness from the effects of pronounceability. The present results stand in contrast to previous research using perceptual comparison tasks, since the earlier work failed to indicate any effect of familiarity.