Prime and probability: causal knowledge affects inferential and predictive effects on self-agency experiences

Experiences of having caused a certain outcome may arise from motor predictions based on action–outcome probabilities and causal inferences based on pre-activated outcome representations. However, when and how both indicators combine to affect such self-agency experiences is still unclear. Based on previous research on prediction and inference effects on self-agency, we propose that their (combined) contribution crucially depends on whether people have knowledge about the causal relation between actions and outcomes that is relevant to subsequent self-agency experiences. Therefore, we manipulated causal knowledge that was either relevant or irrelevant by varying the probability of co-occurrence (50% or 80%) of specific actions and outcomes. Afterwards, we measured self-agency experiences in an action–outcome task where outcomes were primed or not. Results showed that motor prediction only affected self-agency when relevant actions and outcomes were learned to be causally related. Interestingly, however, inference effects also occurred when no relevant causal knowledge was acquired.     

阿尔兹海默病患者中的范畴特异性语义记忆损伤

脑损伤可导致范畴特异性语义损伤, 即某一范畴的语义记忆选择性损伤或损伤更严重。阿尔兹海默病患者中的范畴特异性语义损伤可能来自不同范畴之间在熟悉度、词频、获得年龄、视觉复杂度、语义距离、加工要求以及所涉及的主要语义特征等方面的差别。然而, 有无生命范畴本身是否也是一个来源, 尚不清楚。进一步的研究不仅需要整合范畴途径和特征途径, 并区分语义记忆的存储和通达, 而且需要考查疾病严重程度如何影响语义记忆损伤模式。     

面孔重复启动效应:知觉结构和语义表征的贡献

以30名大学生为被试,探讨了熟悉和陌生的正倒立面孔对重复启动效应的影响,以此考察知觉结构和语义表征对面孔重复启动的贡献.结果表明:(1)熟悉面孔的重复启动既存在知觉启动也存在语义启动,而不熟悉面孔仅仅存在知觉启动.(2)知觉结构和语义表征对启动效应的贡献是联合的,而不是分离的;在熟悉面孔中,语义表征对重复启动的贡献大于知觉结构的贡献.(3)知觉结构和语义表征对重复启动的贡献与加工阶段有关.知觉结构在初始阶段起作用,随后作用逐渐减弱;而语义表征存在于信息加工的整个过程.     

No evidence for a cue mismatch in negative priming

An experiment is reported in which the cue mismatch hypothesis of negative priming, an important novel variant of the mismatching hypothesis, was tested. A cue mismatch and a no mismatch condition were contrasted in a visual discrimination task. In the prime display of cue mismatch ignored-repetition trials, the colour of the prime distractor was different from the colour of the cue indicating the selection feature (coloured square). In probe displays, cue and repeated stimulus had the same colour. In the no mismatch condition, the visual cue was neutral in terms of colour (always black), so that there was always no cue mismatch between prime and probe displays. Contrary to the prediction of the cue mismatch hypothesis, the negative priming effect was not larger in the cue mismatch than in the no mismatch condition. The cue mismatch hypothesis must therefore be rejected. In contrast, the episodic retrieval account is consistent with the results.     

Magnitude of negative priming varies with conceptual task difficulty: Attentional resources are involved in episodic retrieval processes

In a variant of the negative priming (NP) procedure, the larger of two presented animals is to be named in each trial. Eight animals of different sizes are used, which allows a manipulation of conceptual task difficulty in terms of pair distance (difficult: one step, versus easy: three steps) on the series. Distances are varied for prime pairs and probe pairs orthogonally. NP effects were found for easy (wide) probe distances (Experiments 1 and 2) and, additionally, for easy (wide) prime distances (Experiment 2). This pattern is interpreted in terms of different theories of NP, which emphasize either forward-acting (prime to probe) or backward-acting (probe to prime) processes. The present results are most compatible with a backward-acting mechanism defined by the episodic retrieval perspective; they are less compatible with a forward-acting inhibition perspective. The results have implications for resource requirements of retrieval-based accounts of NP.     

Influence of prime lexicality,frequency, and pronounceability on the masked onset priming effect

The present study investigates the origins of the masked onset priming effect (MOPE). There are two alternative interpretations that account for most of the evidence reported on the MOPE, so far. The speech planning account (SP) identifies the locus of the MOPE in the preparation of the speech response. In contrast, the dual-route theory proposes that the effect arises as a result of the processing of the prime by the nonlexical route. In a series of masked onset priming word naming experiments we test the validity of these accounts by manipulating the primes' frequency, their lexical status, and pronounceability. We found consistent MOPEs of similar magnitude with high- and low-frequency prime words as well as with pronounceable nonwords. Contrarily, when primes consisted of unpronounceable consonantal strings the effect disappeared, suggesting that pronounceability of the prime is a prerequisite for the emergence of the MOPE. These results are in accordance with the predictions of the SP account. The pattern of effects obtained in the present study further defines the origins of the MOPE.     

Across-task long-term priming: Interaction of task readiness and automatic retrieval

When humans carry out actions in response to external stimulation, they acquire associations between the stimulus and the action it triggered. When the same stimulus is used in two different tasks, the retrieval of associations compiled in the competing task hampers current performance. Previous research suggests that this across-task priming depends on the task set for the preceding task remaining active across the switch of tasks and, thus, competing with the activations needed for the new task. We present two experiments investigating this notion. Participants switched between two semantic classification tasks. In Experiment 1, participants switched between short runs of the two tasks. Across-task priming was observed on switch and repeat trials. In Experiment 2, participants switched between longer runs of the two tasks. Across-task priming was markedly reduced on repeat trials. The data suggest that whether or not across-task priming affects behaviour after the switch trial depends, amongst others, on whether the task set necessary for the previous task spills into the repeat trials. The implications of these findings for mechanisms of cognitive and mnemonic control are discussed.     

Stimulus/response learning in masked congruency priming of faces: Evidence for covert mental classifications?

Reaction times for categorization of a probe face according to its sex or fame were contrasted as a function of whether the category of a preceding, sandwich-masked prime face was congruent or incongruent. Prime awareness was measured by the ability to later categorize the primes, and this was close to chance and typically uncorrelated with priming. When prime faces were never presented as visible probes within a test, priming was not reliable; when prime faces were also seen as probes, priming was only reliable if visible and masked presentation of faces were interleaved (not simply if primes had been visible in a previous session). In the latter case, priming was independent of experimentally induced face–response or face–category contingencies, ruling out any simple form of stimulus–response learning. We conclude that the reliable masked congruency priming reflects bindings between stimuli and multiple, abstract classifications that can be generated both overtly and covertly.     

Perceptual strength is different from sensorimotor strength: Evidence from the centre–periphery asymmetry in masked priming

Near-threshold prime stimuli can facilitate or hinder responses to target stimuli, creating either a positive compatibility effect (PCE) or a negative compatibility effect (NCE). An asymmetry has been reported between primes presented in near periphery, which produced a PCE, and foveal primes, which produced an NCE under comparable conditions. This asymmetry has been attributed to the difference in retinal sensitivity, but it remains unclear whether this means that equating discrimination performance for primes in fovea and periphery, in order to account for differences in perceptual sensitivity, would make the priming effects the same. Wider work indicates that perceptual ability can dissociate from visuomotor effects, predicting that equating perceptual ability for fovea and periphery would not equate priming. We tested these opposite possibilities by matching discrimination performance for masked Gabor patches in fovea and near periphery (6°) and using these as primes in a masked priming paradigm expected to elicit NCEs. We found the asymmetry remained: NCE for fovea and PCE for periphery. We replicated this with both blocked and randomized procedures to check for attentional effects. We conclude that equating perceptual strength (discriminability) of stimuli does not equate their sensorimotor impact due to differences in the relative importance of different visual pathways and differing temporal dynamics in perceptual and sensorimotor processes.     

The consequences of virtual embodiment for the mental representation of proximity

There is evidence that knowledge about space will reflect the details of how that space is experienced and how people interact with it. In two experiments we demonstrate that memory for items is spatially structured after their locations were learnt in a desktop virtual environment (DVE). The structure was measured using interitem priming of recognition. By comparison in Experiment 2, after the same layout had been learnt using a map display, there was no evidence of spatial structuring in memory. It is concluded that the limited view of space afforded by navigation through an environment, as contrasted with the overview afforded by a map, explains the observed differences in the spatial structuring of interitem associations. Navigation through an environment leads to spatial structuring in memory whereas using a map does not.