Unconscious task set priming with phonological and semantic tasks

Whether unconscious stimuli can modulate the preparation of a cognitive task is still controversial. Using a backward masking paradigm, we investigated whether the modulation could be observed even if the prime was made unconscious in 100% of the trials. In two behavioral experiments, subjects were instructed to initiate a phonological or semantic task on an upcoming word, following an explicit instruction and an unconscious prime. When the SOA between prime and instruction was sufficiently long (84 ms), primes congruent with the task set instruction led to speedier responses than incongruent primes. In the other condition (36 ms), no task set priming was observed. Repetition priming had the opposite tendency, suggesting the observed task set facilitation cannot be ascribed solely to perceptual repetition priming. Our results therefore confirm that unconscious information can modulate cognitive control for currently active task sets, providing sufficient time is available before the conscious decision.     

Visual working memory is enhanced by mixed strategy use and semantic coding

Visual working memory is enhanced by processes related to verbalisation. However, the mechanism underlying this enhancement is unclear. Experiment 1 investigated the potential contribution of the phonological loop of working memory, by assessing the effects of articulatory suppression on two versions of the Visual Patterns Test—one low and one high in availability of verbal coding. The lack of interaction suggested that the phonological loop is not responsible; however, active use of combined verbal and visual strategies, as well as activated semantic knowledge, both appear to be related to increased capacity. Experiment 2 assessed the role of central executive resources. Because central executive suppression removed the benefit of the high verbal coding task version, central executive resources, assumed to relate to the temporary maintenance of multimodal codes in the episodic buffer, appear to underlie the benefit associated with verbalisation.     

Memory and metamemory for semantic information in obsessive-compulsive disorder

Several studies have been conducted on OCD patients' memory and metamemory performance in episodic tasks. However, there is a clear lack of research addressing these issues for semantic memory (i.e., retrieval of information from long-term memory). Although findings regarding a memory deficit is somewhat equivocal, the empirical evidence clearly demonstrates that OCD patients with primarily checking compulsions show reduced confidence in their memory performance. The purpose of the present study was to investigate memory and metamemory performance of checkers in semantic memory domain. We compared checker OCD patients, non-checker OCD patients and normal controls on their ability to retrieve answers to general knowledge questions with a recall as well as a recognition test. We also investigated prospective (feeling-of-knowing (FOK)) and retrospective (confidence) metamemory judgments. Checker OCs were not poorer in retrieving semantic information from long-term memory. Neither were they less confident about their ability to remember currently unrecallable information in the future (FOK judgments) or about the accuracy of retrieved information (confidence judgments). Moreover, accuracy of metamemory judgments were comparable across groups. Overall, our results revealed that checker OCs do not show a memory or metamemory deficit when semantic memory was concerned, suggesting that any memory and metamemory deficit may be special to recently experienced materials.     

Refractoriness and the healthy brain: A behavioural study on semantic access

While many behavioural studies on refractory phenomena in lexical/semantic access have focused on the mechanisms involved in the oral production of names, comprehension tasks have been almost exclusively used in neuropsychological studies on brain damaged patients. We report the results of two experiments on healthy participants conducted by means of speeded word to picture matching tasks. They assess the effects of the same variables examined in the study of refractory access dysphasic patients: semantic distance and word frequency (experiment 1) and presentation rate and serial position effects (experiment 2). Semantic access patients usually show little effect of word frequency but a large semantic distance effect. However, critical in characterising the syndrome as ‘refractory’, effects of presentation rate and serial position should also be present. The experiments involved the use of a deadline response procedure. The critical manipulation was the absence of a Response Stimulus Interval (RSI) in the fast presentation rate conditions; slower presentation rates involved 1 s RSI. With these manipulations the typical behavioural pattern of performance provided by semantic access dysphasic patients was reproduced. Semantic distance effects were more powerful than word frequency effects (experiment1). Presentation rate effects were found and, most important for a “refractory” account of the effects, a serial position effect was obtained (experiment 2). These results provide the first evidence of such a broad range of refractory effects at the same time in comprehension tasks in healthy subjects and support a purely semantic account for the locus of refractoriness. Moreover, error analysis showed a predominance of perseverative errors with subsequent representations of the same target, supporting a failure of cognitive control mechanisms as the cause of refractory behaviour. The findings are discussed in the light of current models of lexical and semantic processing.     

Processing of representations in declarative and procedural working memory

The article investigates the relation between declarative and procedural working memory (WM; Oberauer, 2009). Two experiments test the assumption that representations in the two subsystems are selected for processing in analogous ways. Participants carried out a series of decisions on memorized lists of digits. For each decision, they had to select declarative and procedural representations. Regarding declarative representations, participants selected a memory set and a digit within this set as the input to each decision. With respect to the procedural representations, they selected a task set to be applied to the selected digit and a response within that task set. We independently manipulated the number of lists and the number of tasks to be switched among (one, two, or three; Experiment 1) and preparation time for a list switch (Experiment 2). For three effects commonly observed in task-switch studies, analogues in declarative WM were found: list-switch costs, mixing costs, and residual switch costs. List- and task-switch costs were underadditive, suggesting that declarative and procedural representations are selected separately and in parallel. The findings support the hypothesis of two analogous WM subsystems.     

Configural learning without reinforcement: Integrated memories for correlates of what,where, and when

In 2 experiments we examined the ability of rats to form configural memories of what auditory stimulus (X or Y) was presented where (Context A or B) and when (morning or afternoon). In both experiments, rats received morning presentations of X in Context A and Y in Context B and afternoon presentations of X in B and Y in A. Subsequently, at midday the rats were exposed to trials where X was paired with footshock whereas Y was not. We then assessed the degree of contextual fear in A and B in the morning and the afternoon. In the morning, rats showed more fear in A than in B, and in the afternoon they showed more fear in B than in A. These results indicate that rats can form configural memories that represent what (X or Y) was presented, where (A or B), and when (morning or afternoon).     

Selection of objects and tasks in working memory

When people hold several objects (such as digits or words) in working memory and select one for processing, switching to a new object takes longer than selecting the same object as that on the preceding processing step. Similarly, selecting a new task incurs task- switching costs. This work investigates the selection of objects and of tasks in working memory using a combination of object-switching and task-switching paradigms. Participants used spatial cues to select one digit held in working memory and colour cues to select one task (addition or subtraction) to apply to it. Across four experiments the mapping between objects and their cues and the mapping between tasks and their cues were varied orthogonally. When mappings varied from trial to trial for both objects and tasks, switch costs for objects and tasks were additive, as predicted by sequential selection or resource sharing. When at least one mapping was constant across trials, allowing learning of long-term associations, switch costs were underadditive, as predicted by partially parallel selection. The number of objects in working memory affected object-switch costs but not task-switch costs, counter to the notion of a general resource of executive attention.     

Sticky plans: Inhibition and binding during serial-task control

Recent evidence suggests substantial response-time costs associated with lag-2 repetitions of tasks within explicitly controlled task sequences [Koch, I., Philipp, A. M., Gade, M. (2006). Chunking in task sequences modulates task inhibition. Psychological Science, 17, 346-350; Schneider, D. W. (2007). Task-set inhibition in chunked task sequences. Psychonomic Bulletin & Review, 14, 970-976], a result that has been interpreted as inhibition of no-longer relevant tasks. Experiments 1-3 confirm much larger lag-2 costs under serial-control than under externally cued conditions, but also show (a) that these costs occur only when sequences contain at least two distinct chunks and (b) that direct lag-2 repetitions are not a necessary condition for their occurrence. This pattern suggests the hypothesis that rather than task-set inhibition, the large lag-2 costs observed in complex sequences, reflect interference resulting from links between positions within a sequential plan and the individual tasks controlled by this plan. The remaining experiments successfully test this hypothesis (Experiment 4), rule out chaining accounts as a potential alternative explanation (Experiment 5), and demonstrate that interference results from information stored in long-term memory rather than working memory (Experiment 6). Implications of these results for an integration of models of serial-order control and serial memory are discussed.     

Autobiographical memory and well-being in aging: The central role of semantic self-images

Higher levels of well-being are associated with longer life expectancies and better physical health. Previous studies suggest that processes involving the self and autobiographical memory are related to well-being, yet these relationships are poorly understood. The present study tested 32 older and 32 younger adults using scales measuring well-being and the affective valence of two types of autobiographical memory: episodic autobiographical memories and semantic self-images. Results showed that valence of semantic self-images, but not episodic autobiographical memories, was highly correlated with well-being, particularly in older adults. In contrast, well-being in older adults was unrelated to performance across a range of standardised memory tasks. These results highlight the role of semantic self-images in well-being, and have implications for the development of therapeutic interventions for well-being in aging.     

Phonological and semantic information in adults' orthographic learning

A training paradigm was used to assess the early stages of the acquisition of novel letter strings in adults. Provision of either phonological or semantic information during training improved spelling recognition (Experiment 1). Manipulation of the processing required during training (phonological, semantic, or both) produced no consistent effects on spelling when both phonology and meaning were provided (Experiment 2). An advantage of phonological over orthographic processing on spelling recognition and cued recall was found when meaning was provided during training but phonology was not (Experiment 3). The experiments support the role of phonological information in early learning of orthography, but additional research is required to clarify when and how semantic information supports the formation of new orthographic representations.     

Prevalence and determinants of direct and generative modes of production of episodic future thoughts in the word cueing paradigm

Recent research suggests that episodic future thoughts can be formed through the same dual mechanisms, direct and generative, as autobiographical memories. However, the prevalence and determinants of the direct production of future event representations remain unclear. Here, we addressed this issue by collecting self-reports of production modes, response times (RTs), and verbal protocols for the production past and future events in the word cueing paradigm. Across three experiments, we found that both past and future events were frequently reported to come directly to mind in response to the cue, and RTs confirmed that events were produced faster for direct than for generative responses. When looking at the determinants of direct responses, we found that most past and future events that were directly produced had already been thought of on a previous occasion, and the frequency of previous thoughts predicted the occurrence of direct access. The direct production of autobiographical thoughts was also more frequent for past and future events that were judged important and emotionally intense. Collectively, these findings provide novel evidence that the direct production of episodic future thoughts is frequent in the word cueing paradigm and often involves the activation of personally significant “memories of the future.”     

Fact learning: How information accuracy,delay, and repeated testing change retention and retrieval experience

Previous classroom studies have shown that the phenomenology of studied facts changes over time. However, pedagogical needs preclude both the study of errors and the separation of the effects that delay and repeated testing have on retention and retrieval experience. We addressed these issues together in an experiment where participants read stories containing correct and misleading information and provided Remember, Just Know, and Familiar judgements on immediate and delayed general knowledge tests. After 2 days, information learned from the stories shifted from Remembered to Just Known, but repeated testing attenuated this shift. Interestingly, similar patterns of retrieval and phenomenology were observed for correct and misleading information with one important difference—the shift over time to Just Knowing was significantly greater for correct than for misleading information. Together, these findings show the roles of information accuracy, delay, and testing in determining both retention and the subjective experience of retrieval.     

Physiological, psychological and behavioral consequences of activating autobiographical memories

Activating an autobiographical memory for a specific childhood event can have immediate and robust physiological, psychological, and behavioral consequences. The target behavior was public speaking, a vital skill about which many people are socially anxious. In this study, it was suggested to subjects that they had a positive public speaking experience in early childhood; they then thought about and retrieved details of this true childhood memory. Compared to a control condition in which a different suggestion was made, subjects in the treatment group exhibited superior public speaking performance on the Trier Social Stress Test (TSST). Further, physiological measures of cortisol and a self-report measure of anxiety (STAI-S) reflected a significantly smaller increase in anxiety from before to after the TSST in the treatment than control condition. Activating autobiographical memory for an event increases the accessibility of that memory and consequently affects performance on related behaviors.     

Category specificity in normal episodic learning: applications to object recognition and category-specific agnosia

Studies of patients with category-specific agnosia (CSA) have given rise to multiple theories of object recognition, most of which assume the existence of a stable, abstract semantic memory system. We applied an episodic view of memory to questions raised by CSA in a series of studies examining normal observers' recall of newly learned attributes of familiar objects. Subjects first learned to associate arbitrarily assigned colors or textures to objects in a training phase, and then attempted to report the newly learned attribute of each object in a recall task. Our subjects' pattern of recall errors was similar both quantitatively and qualitatively to the identification deficits among patients with CSA for biological objects. Furthermore, errors tended to reflect conceptually and structurally based confusions. We suggest that object identification involves recruitment and integration of information across distributed episodic memories and that this process is susceptible to interference from objects that are structurally similar and conceptually related.     

Novel word integration in the mental lexicon: Evidence from unmasked and masked semantic priming

We sought to establish whether novel words can become integrated into existing semantic networks by teaching participants new meaningful words and then using these new words as primes in two semantic priming experiments, in which participants carried out a lexical decision task to familiar words. Importantly, at no point in training did the novel words co-occur with the familiar words that served as targets in the primed lexical decision task, allowing us to evaluate semantic priming in the absence of direct association. We found that familiar words were primed by the newly related novel words, both when the novel word prime was unmasked (Experiment 1) and when it was masked (Experiment 2), suggesting that the new words had been integrated into semantic memory. Furthermore, this integration was strongest after a 1-week delay and was independent of explicit recall of the novel word meanings: Forgetting of meanings did not attenuate priming. We argue that even after brief training, newly learned words become an integrated part of the adult mental lexicon rather than being episodically represented separately from the lexicon.     

Task choice and semantic interference in picture naming

Evidence from dual-task performance indicates that speakers prefer not to select simultaneous responses in picture naming and another unrelated task, suggesting a response selection bottleneck in naming. In particular, when participants respond to tones with a manual response and name pictures with superimposed semantically related or unrelated distractor words, semantic interference in naming tends to be constant across stimulus onset asynchronies (SOAs) between the tone stimulus and the picture–word stimulus. In the present study, we examine whether semantic interference in picture naming depends on SOA in case of a task choice (naming the picture vs reading the word of a picture–word stimulus) based on tones. This situation requires concurrent processing of the tone stimulus and the picture–word stimulus, but not a manual response to the tones. On each trial, participants either named a picture or read aloud a word depending on the pitch of a tone, which was presented simultaneously with picture–word onset or 350 ms or 1000 ms before picture–word onset. Semantic interference was present with tone pre-exposure, but absent when tone and picture-word stimulus were presented simultaneously. Against the background of the available studies, these results support an account according to which speakers tend to avoid concurrent response selection, but can engage in other types of concurrent processing, such as task choices.     

Event memory and misinformation effects in a gorilla (<Emphasis Type="Italic">Gorilla gorilla gorilla</Emphasis>)

Event memory and misinformation effects were examined in an adult male gorilla ( Gorilla gorilla gorilla). The gorilla witnessed a series of unique events, involving a familiar person engaging in a novel behavior (experiment 1), a novel person engaging in a novel behavior (experiment 2), or the presentation of a novel object (experiment 3). Following a 5- to 10-min retention interval, a tester gave the gorilla three photographs mounted on wooden cards: a photograph depicting the correct person or object and two distractor photographs drawn from the same class. The gorilla responded by returning a photograph. If correct, he was reinforced with food. Across three experiments, the gorilla performed significantly above chance at recognizing the target photograph. In experiment 4, the gorilla showed at-chance performance when the event was followed by misinformation (a class-consistent, but incorrect photograph), but significantly above-chance performance when no misinformation occurred (either correct photograph or no photograph). Although the familiarity can account for these data, they are also consistent with an episodic-memory interpretation.     

Effects of saccadic bilateral eye movements on memory in children and adults: an exploratory study

The effects of saccadic bilateral (horizontal) eye movements on true and false memory in adults and children were investigated. Both adults and children encoded lists of associated words in the Deese-Roediger-McDermott paradigm followed by a test of recognition memory. Just prior to retrieval, participants were asked to engage in 30s of bilateral vs. vertical vs. no eye movements. For studied information, the results for adults replicated previous work; bilateral eye movements were demonstrated to increase the accuracy of memory by increasing the hit rate and reducing the false alarm rate for related and unrelated recognition test lures. The results for children also indicated an improvement in memory accuracy, and like adults, was due to both an increase in the hit rate and a reduction in the false alarm rate. In spite of these similarities, the effects of bilateral eye movements differed between adults and children for critical unstudied words; i.e., those associated with the theme of the list. Only in adults did, bilateral eye movements reduce associative false memories; children did not show a reduction in false memory for critical associates. This produced a dissociation between the effects of eye movements on associative false memory as a function of age. The results are discussed from a developmental perspective in terms of potential mechanisms underlying true and false memory.     

Category size effects revisited: frequency and masked priming effects in semantic categorization

Previous work indicates that semantic categorization decisions for nonexemplars (e.g., deciding that TURBAN is not an animal name) are faster for high-frequency words than low-frequency words. However, there is evidence that this result might depend on category size. When narrow categories are used (e.g., Months, Numbers), there is no frequency effect for nonexemplars. This result is confirmed, and is explained in terms of a category search model, which allows a "No" decision to be generated without access to the lexical entry for the target word. This explains the absence of a frequency effect, but not the presence of a strong masked repetition priming effect, which is assumed to have a lexical source. It is shown that this effect may not be lexical, since nonwords also show similar priming. Both of these priming effects disappear when a larger category is used. This pattern of results is explained on the assumption that category search is only possible with small categories, and that tentative category decisions are generated for the unconsciously perceived prime, which leads to a marked response congruence effect.     

Characteristics of intrusive memories in a community sample of depressed, recovered depressed and never-depressed individuals

An accumulating body of evidence has revealed that intrusive autobiographical memories of negative events play a role in depression. Despite increasing understanding of the phenomenological experience of these memories, previous research in this area has been conducted in either nonclinical samples, or in clinical samples without an adequate control group. This study aimed to replicate and extend findings with dysphoric samples by comparing the content and characteristics of intrusive memories in clinically depressed (n = 25), recovered (n = 30) and never-depressed (n = 30) participants. Participants completed mood measures, and a battery of self-report questionnaires that indexed intrusive memory frequency, avoidance and characteristics. Intrusive memories were common and shared strikingly similar characteristics across the three groups. The key finding was that depressed participants reported higher levels of intrusion-related distress, associated emotions (especially sadness and helplessness), interference as a result of the memories and memory vividness compared to the never-depressed group. Despite similar levels of intrusion, there were group differences in avoidance such that depressed participants reported higher levels of avoidance than the never-depressed group. These results provide further support for the proposal that clinical interventions for depression could usefully incorporate components that aim to reduce intrusive autobiographical memories and target avoidance strategies.