Emotion-induced modulation of recognition memory decisions in a Go/NoGo task: Response bias or memory bias?

In recognition memory tests for words, items with negative emotional meaning are more often classified as “old” compared to neutral items, whether or not they are in fact old. Two accounts for this bias have been offered: One proposes that emotions disrupt retrieval and response monitoring processes (executive control account), the other proposes that emotions cause illusory feelings of remembering (memory bias account). We addressed this issue by varying the target signal in a Go/NoGo variant of a recognition memory task for negative, neutral, and positive words and faces: One group of participants was asked to respond to old items whereas the other group was asked to respond to new items. Results showed that the “Go-for-old” group showed the typical emotion-induced response bias shift for both positive and negative words, while the “Go-for-new” group showed the opposite pattern. Results were nonsignificant for faces, but went into the same direction. The findings are clearly inconsistent with the executive control account and speak for a genuine memory illusion induced by emotional arousal.     

Can we have a distinctive theory of memory?

The current status of the concept of distinctiveness an applied to memory research is discussed. In spite of the fact that distinctiveness is difficult to define, an increasing number of memory phenomena have been explained in terms of distinctiveness. These phenomena are grouped into four classes, which vary in how distinctiveness is operationalized. Distinctiveness has different effects on memory performance, depending on how it is defined, suggesting that the concept of distinctiveness has been overapplied. In addition, current theoretical explanations of the effects of distinctiveness on memory fail to specify what the different definitions of distinctiveness have in common, and fail to encompass adequately the broad range of phenomena to be explained. A limited theory of distinctiveness is proposed, in order to explain why conceptually incongruent material is remembered well.     

Effects of stimulus–stimulus short-term memory associations in a Simon-like task

The Simon effect refers to faster responding when an irrelevant stimulus location corresponds with the response to a relevant stimulus attribute than when it does not. We investigated whether a memory-based Simon-like effect would occur when the irrelevant spatial attribute was associated with the stimulus during a prior task. In a first task, an association between colour and location was formed by requiring participants to count the occurrences of two colour stimuli, each of which was always presented in a left or right location. In a second task, the colour stimuli were presented centrally and mapped to left and right keypresses, with the mapping being inconsistent or consistent with the prior colour-location associations. A Simon-like effect was evident at the start of the second task, with performance being better when the established colour–position associations were consistent with the colour–response mapping than when they were not. This result indicates that stimulus–stimulus short-term memory associations formed during the first task transferred to the second task. For the remainder of the second task, the data showed a more conservative speed–accuracy criterion for the inconsistent condition than for the consistent condition, though a processing efficiency measure suggested that the prior stimulus–stimulus short-term associations may also continue to directly influence performance. Results suggest that simple declarative knowledge, as represented by stimulus–stimulus STM links, exerts less persistent transfer effects than procedural knowledge as provided by stimulus–response STM links.     

Integrated cross-domain object storage in working memory: Evidence from a verbal–spatial memory task

Working-memory theories often include domain-specific verbal and visual stores (e.g., the phonological and visuospatial buffers of Baddeley, 1986), and some also posit more general stores thought to be capable of holding verbal or visuospatial materials (Baddeley, 2000; Cowan, 2005). However, it is currently unclear which type of store is primarily responsible for maintaining objects that include components from multiple domains. In these studies, a spatial array of letters was followed by a single probe identical to an item in the array or differing systematically in spatial location, letter identity, or their combination. Concurrent verbal rehearsal suppression impaired memory in each of these trial types in a task that required participants to remember verbal–spatial binding, but did not impair memory for spatial locations if the task did not require verbal–spatial binding for a correct response. Thus, spatial information might be stored differently when it must be bound to verbal information. This suggests that a cross-domain store such as the episodic buffer of Baddeley (2000) or the focus of attention of Cowan (2001) might be used for integrated object storage, rather than the maintenance of associations between features stored in separate domain-specific buffers.     

Is task interference in event-based prospective memory dependent on cue presentation?

Whether having an intention produces a performance cost to ongoing activities (task interference) is central to theoretical claims regarding the mechanisms underlying cue detection in event-based prospective memory. Recent evidence suggests that task interference primarily reflects an attention allocation policy stored in memory when intentions are encoded. The present study examined whether these policies can change with ongoing task experience. In Experiment 1, task interference was more greatly reduced when expected cues were not presented than when they were. Experiment 2 replicated this effect when the importance of the prospective memory task was emphasized. In Experiment 3, task interference decreased with time, and this decrease was greater when expected cues were not presented than when they were. Cue presentation is crucial to maintenance of attention allocation policies established by task instructions. This is the first article to demonstrate changes in task interference with ongoing task experience without forewarning individuals of the relevance of upcoming ongoing task trials to intentions.     

Can skilled readers perform a second task in parallel? A functional connectivity MRI study

When asked to search for a target letter while reading, the patterns with which people miss the target letter reveal information about the process of reading itself. Questions remain as to whether this paradigm reflects normal reading processes however. We used a novel continuous-performance neuroimaging paradigm to address this question. In separate scanning runs, subjects either read alone, read while searching for a target letter, or searched non-words continuously. Functional connectivity analysis recovered the full extent of brain areas identified for reading in a localizer scan, with no differences between reading alone and the dual task condition. Differences were found, however, between both reading conditions and the nonword search condition. These results demonstrate that in skilled readers brain activation associated with reading is unaffected by a concurrent letter-search task. They further demonstrate the utility of a naturalistic, continuous-performance paradigm for studying the neural basis of language processing.     

Can the memory enhancement of the survival judgment task be explained by the elaboration hypothesis?: Evidence from a memory load paradigm1

Many reports have described a survival judgment task that requires participants to judge words according to their relevance to a survival situation, eliciting better recall than that obtained in other judgment tasks (e.g., semantic or self‐judgment tasks). Two explanatory hypotheses (the adaptive hypothesis and the elaboration hypothesis) have been proposed. Here we used the memory load paradigm to investigate whether the adaptive hypothesis or the combination hypothesis can better account for the memory enhancement of the survival judgment task. We used a survival judgment task and an autobiographical recall task with the condition of no memory load or memory load. The 48 participants performed four encoding conditions (memory load—survival, no memory load—survival, memory load—autobiographical, and no memory load—autobiographical). The results showed that memory enhancement of the survival judgment task occurred only in the no memory load condition, but not in the memory load condition. Our results support the elaboration hypothesis. We also discuss the validity of the elaboration hypothesis and future directions to be pursued in this research field.     

Implicit task sets in task switching?

In 2 experiments, the authors compare stimulus-based versus task-rule-based task performance. Participants practiced 8 stimulus-response mappings either with or without knowledge about 2 underlying task sets. After practice, 2 transfer blocks with 8 new stimuli were presented. Results show that rule knowledge leads to significant switch and transfer costs, whereas without rule knowledge neither switch nor transfer costs occur. However, significant Task Type x Response Type interactions occurred in both conditions. In a second experiment including only the no rule condition, half of the stimulus-response mappings in the transfer blocks were incongruent to the underlying task rule. Slower response times for these incongruent stimuli as compared with congruent stimuli and the absence of switch costs suggest that participants acquired (presumably implicit) knowledge about 4 different stimulus-response categories.     

Do Clark’s nutcrackers demonstrate what-where-when memory on a cache-recovery task?

What-where-when (WWW) memory during cache recovery was investigated in six Clark’s nutcrackers. During caching, both red- and blue-colored pine seeds were cached by the birds in holes filled with sand. Either a short (3 day) retention interval (RI) or a long (9 day) RI was followed by a recovery session during which caches were replaced with either a single seed or wooden bead depending upon the color of the cache and length of the retention interval. Knowledge of what was in the cache (seed or bead), where it was located, and when the cache had been made (3 or 9 days ago) were the three WWW memory components under investigation. Birds recovered items (bead or seed) at above chance levels, demonstrating accurate spatial memory. They also recovered seeds more than beads after the long RI, but not after the short RI, when they recovered seeds and beads equally often. The differential recovery after the long RI demonstrates that nutcrackers may have the capacity for WWW memory during this task, but it is not clear why it was influenced by RI duration.     

Does overgeneral autobiographical memory result from poor memory for task instructions?

Considerable previous research has shown that retrieval of overgeneral autobiographical memories (OGM) is elevated among individuals suffering from various emotional disorders and those with a history of trauma. Although previous theories suggest that OGM serves the function of regulating acute negative affect, it is also possible that OGM results from difficulties in keeping the instruction set for the Autobiographical Memory Test (AMT) in working memory, or what has been coined "secondary goal neglect" (Dalgleish, 2004). The present study tested whether OGM is associated with poor memory for the task's instruction set, and whether an instruction set reminder would improve memory specificity over repeated trials. Multilevel modelling data-analytic techniques demonstrated a significant relationship between poor recall of instruction set and probability of retrieving OGMs. Providing an instruction set reminder for the AMT relative to a control task's instruction set improved memory specificity immediately afterward.     

Does overgeneral autobiographical memory result from poor memory for task instructions?

Considerable previous research has shown that retrieval of overgeneral autobiographical memories (OGM) is elevated among individuals suffering from various emotional disorders and those with a history of trauma. Although previous theories suggest that OGM serves the function of regulating acute negative affect, it is also possible that OGM results from difficulties in keeping the instruction set for the Autobiographical Memory Test (AMT) in working memory, or what has been coined “secondary goal neglect” (Dalgleish, 2004). The present study tested whether OGM is associated with poor memory for the task's instruction set, and whether an instruction set reminder would improve memory specificity over repeated trials. Multilevel modelling data-analytic techniques demonstrated a significant relationship between poor recall of instruction set and probability of retrieving OGMs. Providing an instruction set reminder for the AMT relative to a control task's instruction set improved memory specificity immediately afterward.     

Can time-based decay explain temporal distinctiveness effects in task switching?

In task switching, extending the response–cue interval (RCI) reduces the switch cost—the detriment to performance when switching compared to repeating tasks. This reduction has been used as evidence for the existence of task-set decay processes. Recently, this has been challenged by the observation of sequential dependencies on the RCI effect: switch cost is only reduced at longer RCIs when the previous trial had a short RCI. This trial-wise variation of RCI is thought to affect the temporal distinctiveness (TD) of a previous task's episodic trace, affecting the probability of its automatic retrieval on the current trial; importantly, TD is thought to be independent of the current trial's RCI. The present study highlights a dependency between the current RCI and TD, and demonstrates that a decay model can reproduce some patterns of data attributed to TD. Further, the decay account makes a strong prediction when TD is held constant: repetition response times should slow as the RCI increases, and switch response times should be facilitated. This prediction was tested via re-analysis of extant data and three experiments. The re-analysis provided some evidence for the decay account, but Experiments 1 and 2 report slowing for task repetition and switch trials, which cannot be explained by a task-set decay process. Experiment 3, which utilized tasks requiring perceptual judgements, showed small evidence for decay. We conclude that the data are largely consistent with the TD account and that the evidence for decay of higher-level task-sets is not convincing.     

Can dogs use vocal intonation as a social referencing cue in an object choice task?

Evidence from the literature indicates that dogs’ choices can be influenced by human-delivered social cues, such as pointing, and pointing combined with facial expression, intonation (i.e., rising and falling voice pitch), and/or words. The present study used an object choice task to investigate whether intonation conveys unique information in the absence of other salient cues. We removed facial expression cues and speech information by delivering cues with the experimenter’s back to the dog and by using nonword vocalizations. During each trial, the dog was presented with pairs of the following three vocal cues: Positive (happy-sounding), Negative (sad-sounding), and Breath (neutral control). In Experiment 1, where dogs received only these vocal cue pairings, dogs preferred the Positive intonation, and there was no difference in choice behavior between Negative or Breath. In Experiment 2, we included a point cue with one of the two vocal cues in each pairing. Here, dogs preferred containers receiving pointing cues as well as Negative intonation, and preference was greatest when both of these cues were presented together. Taken together, these findings indicate that dogs can indeed extract information from vocal intonation alone, and may use intonation as a social referencing cue. However, the effect of intonation on behavior appears to be strongly influenced by the presence of pointing, which is known to be a highly salient visual cue for dogs. It is possible that in the presence of a point cue, intonation may shift from informative to instructive.     

Can tutoring improve performance on a reasoning task under deadline conditions?

The present study examined the effectiveness of a tutoring technique that has been used to identify and address participants' misunderstandings in Wason's selection task. In particular, the study investigated whether the technique would lead to improvements in performance when the task was presented in a deadline format (a condition in which time restrictions are imposed). In Experiment 1, the effects of tutoring on performance were compared in free time (conditions in which no time restrictions are imposed) and deadline task formats. In Experiment 2, improvements in performance were studied in deadline task formats, in which the tutoring and test phases were separated by an interval of 1 day. The results suggested that tutoring improved performance on the selection task under deadline and in free time conditions. Additionally, the study showed that participants made errors because they had misinterpreted the task. With tutoring, they were able to modify their initial misunderstandings.     

Did the popsicle melt? Preschoolers’ performance in an episodic-like memory task

Episodic memory has been tested in non-human animals using depletion paradigms that assess recollection for the “what”, “where” and “when” (i.e., how long ago). This paradigm has not been used with human children, yet doing so would provide another means to explore their episodic memory development. Using a depletion paradigm, preschool-aged children were presented in two trials with a preferred food that was only edible after a short interval and a less-preferred food that was edible after the short and long intervals. Younger (mean?=?40 months) and older (mean?=?65 months) children tended to choose their preferred food after the short intervals, but did not switch to selecting their less-preferred food after the long intervals. Importantly, their choices did not differ with age. Although older children better remembered “what”, “where”, and “what is where” than did younger children, neither age group successfully estimated “how long ago” an event occurred. Finally, both age groups spontaneously recalled information about Trial 1. We also analysed the relation between the different measures used in the study but no clear patterns emerged. Results are discussed with respect to the cognitive mechanisms necessary to succeed in depletion paradigms and the measurement of episodic memory more broadly.     

Flexibility of working memory encoding in a sentence–picture–sound verification task

Dual-process accounts of working memory have suggested distinct encoding processes for verbal and visual information in working memory, but encoding for nonspeech sounds (e.g., tones) is not well understood. This experiment modified the sentence–picture verification task to include nonspeech sounds with a complete factorial examination of all possible stimulus pairings. Participants studied simple stimuli–pictures, sentences, or sounds–and encoded the stimuli verbally, as visual images, or as auditory images. Participants then compared their encoded representations to verification stimuli–again pictures, sentences, or sounds–in a two-choice reaction time task. With some caveats, the encoding strategy appeared to be as important or more important than the external format of the initial stimulus in determining the speed of verification decisions. Findings suggested that: (1) auditory imagery may be distinct from verbal and visuospatial processing in working memory; (2) visual perception but not visual imagery may automatically activate concurrent verbal codes; and (3) the effects of hearing a sound may linger for some time despite recoding in working memory. We discuss the role of auditory imagery in dual-process theories of working memory.     

Is there a search in fixed-set memory search?

We discuss the hypothesis that structural factors in the fixed-set memory-search task may contribute to the standard linear set-size effect typically observed in this task. We constructed a lexical decision task that contained the same structural factors as the memory-search task. Two structural factors are discussed: (1) the priming of the probe by the memory set, and (2) the confounding of repetitions per item with set size. Our experiment demonstrated that these structural factors play a role in the set-size effect. The implications of these effects for the memory-search task and for models proposed to account for memory-search data are discussed.     

Procedural memory effects in categorization: Evidence for multiple systems or task complexity?

According to an influential multiple-systems model of category learning, an implicit procedural system governs the learning of information-integration category structures, whereas a rule-based system governs the learning of explicit rule-based categories. Support for this idea has come in part from demonstrations that motor interference, in the form of inconsistent mapping between response location and category labels, results in observed deficits, but only for learning information-integration category structures. In this article, we argue that this response location manipulation results in a potentially more cognitively complex task in which the feedback is difficult to interpret. In one experiment, we attempted to attenuate the cognitive complexity by providing more information in the feedback, and demonstrated that this eliminates the observed performance deficit for information-integration category structures. In a second experiment, we demonstrated similar interference of the inconsistent mapping manipulation in a rule-based category structure. We claim that task complexity, and not separate systems, might be the source of the original dissociation between performance on rule-based and information-integration tasks.     

Number perseveration in healthy subjects: Does prolonged stimulus exposure influence performance on a serial addition task?

Perseverative behavior characterizes mainly patients with severe psychopathology, but it can also be observed in healthy individuals. The aim of the reported experiment was to investigate a serial addition task that elicits strong perseverative behavior in normal subjects by examining the significance of perseveration in the final step of this addition task (Gardner, 1971) as a function of time availability. The classical serial addition task, which was used in the experiment, consisted of 4 consecutive digit decreases in the added numbers following a constant digit (1,000 + 40 + 1,000 + 30 + 1,000 + 20 + 1,000 + 10) and required an additive calculation. The main questions were how and if color and time variations could influence perseverative responses in this task and whether memory performance and relevant mathematical knowledge of the participants could have an effect on responses. The sample of subjects participating in the experiment consisted of 300 healthy university students (112 male, 188 female) ranging from 17 to 40 years of age. They were divided in 5 groups of 60 subjects each. A memory digit span and spatial test were administered and relevant scores were taken for each subject of the 5 groups. Obtained results suggest the presence of a strong perseverative error in the final step of the presentation of digits for the large majority of subjects and for all 5 conditions. It seems that time and color changes and the memory span of the participants have no detectable effect on performance on this specific serial addition task.