The relationship between strategic control and conscious structural knowledge in artificial grammar learning

We address Jacoby’s (1991) proposal that strategic control over knowledge requires conscious awareness of that knowledge. In a two-grammar artificial grammar learning experiment all participants were trained on two grammars, consisting of a regularity in letter sequences, while two other dimensions (colours and fonts) varied randomly. Strategic control was measured as the ability to selectively apply the grammars during classification. For each classification, participants also made a combined judgement of (a) decision strategy and (b) relevant stimulus dimension. Strategic control was found for all types of decision strategy, including trials where participants claimed to lack conscious structural knowledge. However, strong evidence of strategic control only occurred when participants knew or guessed that the letter dimension was relevant, suggesting that strategic control might be associated with – or even causally requires – global awareness of the nature of the rules even though it does not require detailed knowledge of their content.     

Measuring strategic control in artificial grammar learning

In response to concerns with existing procedures for measuring strategic control over implicit knowledge in artificial grammar learning (AGL), we introduce a more stringent measurement procedure. After two separate training blocks which each consisted of letter strings derived from a different grammar, participants either judged the grammaticality of novel letter strings with respect to only one of these two grammars (pure-block condition), or had the target grammar varying randomly from trial to trial (novel mixed-block condition) which required a higher degree of conscious flexible control. Random variation in the colour and font of letters was introduced to disguise the nature of the rule and reduce explicit learning. Strategic control was observed both in the pure-block and mixed-block conditions, and even among participants who did not realise the rule was based on letter identity. This indicated detailed strategic control in the absence of explicit learning.     

Methodological vs. strategic control in artificial grammar learning: A commentary on Norman, Price and Jones (2011)

Norman et al. (2011) reported that participants exposed in succession to two artificial grammars could be able to learn implicitly about them, and could apply their knowledge strategically to select which string corresponds to one of these two grammars. In this commentary, I identify an artifact that could account for the learning obtained not only in this study, but also in some previous studies using the same procedures. I claim that more methodological control is needed before jumping to conclusions on the kind of strategic control that could be achieved unconsciously.     

Intentional control based on familiarity in artificial grammar learning

It is commonly held that implicit learning is based largely on familiarity. It is also commonly held that familiarity is not affected by intentions. It follows that people should not be able to use familiarity to distinguish strings from two different implicitly learned grammars. In two experiments, subjects were trained on two grammars and then asked to endorse strings from only one of the grammars. Subjects also rated how familiar each string felt and reported whether or not they used familiarity to make their grammaticality judgment. We found subjects could endorse the strings of just one grammar and ignore the strings from the other. Importantly, when subjects said they were using familiarity, the rated familiarity for test strings consistent with their chosen grammar was greater than that for strings from the other grammar. Familiarity, subjectively defined, is sensitive to intentions and can play a key role in strategic control.     

Reward-priming impacts visual working memory maintenance: Evidence from human electrophysiology

Reward can benefit visual processing of reward-associated objects in a non-strategic way. Recent studies have suggested that such influence extends also to visual working memory (VWM) representations of reward-associated stimuli. However, it is not clear yet which mechanisms underlie the behavioural effects in VWM tasks: reward could directly impact on our ability to maintain representations in VWM or it could influence memory indirectly via priming of attentional selection. To distinguish between these alternatives we measured event-related potential indices of selective attention – the N2pc – and VWM maintenance – the CDA (contralateral delay activity) – while participants completed a VWM task. Results show that reward outcome in one trial caused similarly coloured targets to be strongly represented in VWM in subsequent trials, as expressed in a larger-amplitude CDA This was not preceded by a corresponding effect on attentional selection, in so far as our key manipulation had no impact on the N2pc. In a second experiment, we found that reward priming produced a behavioural benefit that emerged over time, suggesting that the representations of reward-associated items stored in VWM are more resistant to interference and decay. We conclude that when the task stresses VWM maintenance, it is at this representational level that reward will have impact.     

Perceptual constraints and the learnability of simple grammars

Cognitive processes are often attributed to statistical or symbolic general-purpose mechanisms. Here we show that some spontaneous generalizations are driven by specialized, highly constrained symbolic operations. We explore how two types of artificial grammars are acquired, one based on repetitions and the other on characteristic relations between tones ("ordinal" grammars). Whereas participants readily acquire repetition-based grammars, displaying early electrophysiological responses to grammar violations, they perform poorly with ordinal grammars, displaying no such electrophysiological responses. This outcome is problematic for both general symbolic and statistical models, which predict that both types of grammars should be processed equally easily. This suggests that some simple grammars are acquired using perceptual primitives rather than general-purpose mechanisms; such primitives may be elements of a "toolbox" of specialized computational heuristics, which may ultimately allow constructing a psychological theory of symbol manipulation.     

辣食渴求者抑制控制能力的行为和ERP研究

采用事件相关电位(ERP)技术,探讨一般线索Go/Nogo和辣食线索Go/Nogo任务过程中,辣食渴求者和非辣食渴求者的抑制控制能力。（1）行为结果显示,两组被试辣食线索的反应时和错误率无显著差异,均在任务类型上有差异,即对辣食线索的反应更慢;（2）ERP结果显示,在辣食相关线索Go/Nogo任务中辣食渴求者的N2b和P3波幅都显著小于非辣食渴求者,N2a没有差异;在一般线索Go/Nogo任务中,ERP成分没有发现显著差异。结果提示,辣食渴求者只在辣食相关线索的抑制控制能力弱于非辣食渴求者,这可能意味着他们对辣食线索抑制反应的缺失。     

The effect of perceptual distinctiveness on the prospective and retrospective components of prospective memory in young and old adults.

In two experiments, the effect of perceptual distinctiveness of cues on prospective memory performance was examined. Young and older adults completed a visual search task with embedded prospective memory instructions. On each trial, participants were asked to indicate the position of a target letter in a letter string, unless either of two letters previously identified as prospective memory cues was presented. Each prospective cue was associated with a specific response. Perceptual distinctiveness was manipulated by spatially displacing a single letter. The prospective component (successful detection of the cue) and the retrospective memory component (recalling the correct response when a cue is detected) were measured separately. Perceptual displacement of cues modulated performance of the prospective component but not the retrospective component. Young adults successfully detected a larger proportion of cues (prospective component) than older adults. However, there were minimal effects of age and no effect of cue displacement on participants' ability to recall the intention once they detected a cue (retrospective component performance). Results are discussed within the context of current theoretical models of prospective memory.     

The Role of Simple Semantics in the Process of Artificial Grammar Learning

This study investigated the effect of semantic information on artificial grammar learning (AGL). Recursive grammars of different complexity levels (regular language, mirror language, copy language) were investigated in a series of AGL experiments. In the with-semantics condition, participants acquired semantic information prior to the AGL experiment; in the without-semantics control condition, participants did not receive semantic information. It was hypothesized that semantics would generally facilitate grammar acquisition and that the learning benefit in the with-semantics conditions would increase with increasing grammar complexity. Experiment 1 showed learning effects for all grammars but no performance difference between conditions. Experiment 2 replicated the absence of a semantic benefit for all grammars even though semantic information was more prominent during grammar acquisition as compared to Experiment 1. Thus, we did not find evidence for the idea that semantics facilitates grammar acquisition, which seems to support the view of an independent syntactic processing component.     

Bilingualism and age are continuous variables that influence executive function

We analyzed the effects of bilingualism and age on executive function. We examined these variables along a continuum, as opposed to dichotomizing them. We investigated the impact that bilingualism and age have on two measures of executive control (Stroop and Flanker). The mouse-tracking paradigm allowed us to examine the continuous dynamics of the responses as participants completed each trial. First, we found that the Stroop effect was reduced with younger age and higher levels of bilingualism; however, no Bilingualism by Age interaction emerged. Second, after controlling for baseline, the Flanker effect was not influenced by bilingualism or age. These results support the notion that bilingualism is one way of enhancing some aspects of executive function – specifically those related to the Stroop task – across the adult life span. In sum, different levels of bilingualism, and different ages, result in varying degrees of executive function as measured by the Stroop task.     

The independence of letter identity and letter doubling in reading

The ability to read requires processing the letter identities in the word and their order, but it is by no means obvious that our long-term memory representations of words spellings consist of only these dimensions of information. The current investigation focuses on whether we process information about another dimension—letter doubling (i.e., that there is a double letter in WEED)—independently of the identity of the letter being doubled. Two experiments that use the illusory word paradigm are reported to test this question. In both experiments, participants are more likely to misperceive a target word with only singleton letters (e.g., WED) as a word with a double (e.g., WEED) when the target is presented with a distractor that contains a different double letter (e.g., WOOD) than when the distractor does not contain a double letter (e.g., WORD). This pattern of results is not predicted by existing computational models of word reading but is consistent with the hypothesis that written language separately represents letter identity and letter doubling information, as previously shown in written language production. These results support a view that the orthographic representations that underlie our ability to read are internally complex and suggest that reading and writing rely on a common level of orthographic representation.     

Task-based working memory guidance of visual attention

Previous research has established that holding a stimulus in working memory (WM) facilitates the deployment of visual attention to that stimulus relative to other stimuli. The present study examined whether maintaining a specific task in WM would also bias the allocation of attention to the stimuli associated with that task. Participants performed a speeded letter search task while simultaneously keeping in WM one of two task cues shown at the beginning of each trial. The results showed that task-based WM guidance of attention was modulated by response latencies. Whereas the participants with fast reaction times showed little influence of WM contents, the participants with slow reaction times took longer to respond when the letter target appeared in a distractor stimulus consistent with the task cue held in mind. A subsequent Stroop experiment found a larger Stroop interference effect from the participants in the slow group compared with those in the fast group, suggesting that the differential WM effect between the two groups may be associated with an individual's ability to inhibit task-irrelevant information. Taken together, these results expanded the realm of previous research and provided further evidence for a close link between attention and WM.     

Two ways of learning associations

How people learn chunks or associations between adjacent items in sequences was modelled. Two previously successful models of how people learn artificial grammars were contrasted: the CCN, a network version of the competitive chunker of Servan‐Schreiber and Anderson [J. Exp. Psychol.: Learn. Mem. Cogn. 16 (1990) 592], which produces local and compositionally‐structured chunk representations acquired incrementally; and the simple recurrent network (SRN) of Elman [Cogn. Sci. 14 (1990) 179], which acquires distributed representations through error correction. The models' susceptibility to two types of interference was determined: prediction conflicts, in which a given letter can predict two other letters that appear next with an unequal frequency; and retroactive interference, in which the prediction made by a letter changes in the second half of training. The predictions of the models were determined by exploring parameter space and seeing howdensely different regions of the space of possible experimental outcomes were populated by model outcomes. For both types of interference, human data fell squarely in regions characteristic of CCN performance but not characteristic of SRN performance.     

A two‐process model of strategic monitoring in event‐based prospective memory: Activation/retrieval mode and checking

Theorists have suggested that individuals may remember to execute event‐based intended actions by deploying executive or attentional resources to monitor for the markers or target events that indicate that it is appropriate to execute the intended actions (e.g., McDaniel & Einstein, 2000; Shallice & Burgess, 1991), but these strategic monitoring views are not specific about the processes that strategic monitoring entails. A more specific idea is outlined here (see also Guynn, 2001) and an experiment with results consistent with this view is reported. According to this two‐process view, strategic monitoring entails maintaining the cognitive system in a prospective memory retrieval mode, which may be mediated by increased activation of the prospective memory representation, plus checking whether the circumstances to execute the intended action are present. In the current experiment, concurrent task impairment on nontarget trials, on which participants were instructed to press a key if they saw a target event (i.e., experimental trials), relative to trials on which participants were not instructed to press a key if they saw a target event (i.e., control trials), provided a footprint of strategic monitoring. An interaction of trial type and whether the experimental and control trials alternated or were blocked revealed greater impairment on experimental trials relative to control trials when the trials were blocked than when the trials alternated. Performance on experimental trials did not vary whether the trials alternated or were blocked, while performance on control trials was significantly worse when the trials alternated than when the trials were blocked. The results are consistent with the two‐process view and the idea that participants maintained a retrieval mode/activation and checked on experimental trials, neither maintained a retrieval mode/activation nor checked on blocked control trials, and maintained a retrieval mode/activation but did not check on alternating control trials.     

Encoding and output order processes in short-term order recall of distinctive items.

Adults recalled the order of the letters in one of two four-letter segments following a distractor task. They knew in advance the identity of the letters in each segment. A letter was made distinctive by replacing it with a red dash. This unusual form of distinctiveness generally had negative effects on recall of both the segment containing the missing letter and the absent letter within the segment. Encoding and output processes were manipulated by varying precue information and recall order instructions, respectively. Informing participants in advance whether or not a trial would contain a distinctive (i.e., missing) letter depressed recall. Constraining output order eliminated the disadvantage for the absent letter. The results are discussed in terms of encoding and output order processes in short-term recall of order information.     

When the rules are reversed: Action-monitoring consequences of reversing stimulus–response mappings

How does switching tasks affect our ability to monitor and adapt our behavior? Largely independent lines of research have examined how individuals monitor their actions and adjust to errors, on the one hand, and how they are able to switch between two or more tasks, on the other. Few studies, however, have explored how these two aspects of cognitive?Cbehavioral flexibility interact. That is, how individuals monitor their actions when task rules are switched remains unknown. The present study sought to address this question by examining the action-monitoring consequences of response switching??a form of task switching that involves switching the response that is associated with a particular stimulus. We recorded event-related brain potentials (ERPs) while participants performed a modified letter flanker task in which the stimulus?Cresponse (S?CR) mappings were reversed between blocks. Specifically, we examined three ERPs??the N2, the error-related negativity (ERN), and the error positivity (Pe)??that have been closely associated with action monitoring. The findings revealed that S?CR reversal blocks were associated with dynamic alterations of action-monitoring brain activity: the N2 and ERN were enhanced, whereas the Pe was reduced. Moreover, participants were less likely to adapt their posterror behavior in S?CR reversal blocks. Taken together, these data suggest that response switching results in early enhancements of effortful control mechanisms (N2 and ERN) at the expense of reductions in later response evaluation processes (Pe). Thus, when rules change, our attempts at control are accompanied by less attention to our actions.     

Space Fortress game training and executive control in older adults: A pilot intervention

ABSTRACT

We investigated the feasibility of using the Space Fortress (SF) game, a complex video game originally developed to study complex skill acquisition in young adults, to improve executive control processes in cognitively healthy older adults. The study protocol consisted of 36 one-hour game play sessions over 3 months with cognitive evaluations before and after, and a follow-up evaluation at 6 months. Sixty participants were randomized to one of three conditions: Emphasis Change (EC) – elders were instructed to concentrate on playing the entire game but place particular emphasis on a specific aspect of game play in each particular game; Active Control (AC) – game play with standard instructions; Passive Control (PC) – evaluation sessions without game play. Primary outcome measures were obtained from five tasks, presumably tapping executive control processes. A total of 54 older adults completed the study protocol. One measure of executive control, WAIS-III letter–number sequencing, showed improvement in performance from pre- to post-evaluations in the EC condition, but not in the other two conditions. These initial findings are modest but encouraging. Future SF interventions need to carefully consider increasing the duration and or the intensity of the intervention by providing at-home game training, reducing the motor demands of the game, and selecting appropriate outcome measures.     

Detecting the presence of a singleton involves focal attention

It has been claimed that the detection of a feature singleton can be based on activity in a feature map that allows coarse coding that something unique is present in the visual field. In the present study, participants detected the presence or absence of a color singleton. Even though the letter form of the color singleton was task-irrelevant, we showed that repeating the letter form of the singleton resulted in repetition priming on the next trial. Such repetition priming was not found when a nonsingleton letter was repeated as the singleton. Since the letter form of the color singleton could only be picked up by focal attention, the repetition priming effect indicates that focal attention is allocated to the feature singleton even in the simplest present-absent feature detection tasks. We showed that this effect is equally strong in conditions of low and high perceptual load. These results are inconsistent with theories that it is possible to detect a feature singleton without directing some form of attention to its location.     

Testing the Role of Phonology in Reading: Focus on Sentence Processing

Most reading research investigating the role of phonology in word recognition has focused on studies employing an individual word as the sole stimulus. The bulk of such research has offered support for the phonological recoding hypothesis, the conjecture that access to a printed word’s meaning requires activation of the word’s phonology (i.e., meaning is not typically activated via orthography alone). A criticism of such studies is that by presenting participants with only a single word on each experimental trial (a nonecological manipulation), participants may alter their typical strategy of reading in such a way as to artificially favor the phonological recoding hypothesis. The present study avoided a focus on single words by requiring participants to read sentences and paragraphs for comprehension. Experiment 1 showed that, in reading a paragraph of connected sentences, eliminating a letter in a word that altered the phonology was more deleterious than eliminating a letter that did. Experiment 2 focused on the reading of each sentence itself rather than on the paragraph and provided additional control conditions. The results were similar to those of Experiment 1, consistent with the phonological recoding hypothesis.     

Wagering demonstrates subconscious processing in a binary exclusion task

We briefly presented either the letter 'b' or the letter 'h' to participants who were instructed to respond by saying the letter that was not shown. This binary version of the exclusion task avoids problems with assessing baseline completion rates. When the letters were shown for 5-10 ms participants erroneously responded with the shown letter at a rate greater than chance. They were capable of following the instructions when the letter was shown for longer (15 ms). Given the chance to wager low or high on their choices after short duration stimuli, participants declined to wager high even when they were correct. Taken together these results suggest that the briefly presented stimuli were processed subconsciously.