Separating cue encoding from target processing in the explicit task-cuing procedure: Are there "true" task switch effects?

Six experiments were conducted to separate cue encoding from target processing in explicitly cued task switching to determine whether task switch effects could be separated from cue encoding effects and to determine the nature of the representations produced by cue encoding. Subjects were required to respond to the cue, indicating which cue was presented (Experiments 1, 3a, and 4a) or which task was cued (Experiments 2, 3b, and 4b), before performing the cued task on the target. Cue encoding was successfully separated from target processing when the cue response indicated which task was cued but not when it indicated which cue was presented. Task switch effects were found when this separation was successful, suggesting that there are "true" task switch effects independent of cue encoding. Analysis of the conditions required for successful separation suggested that cue encoding results in a semantic categorical representation of the task to be performed rather than verbal or phonological representations of individual cues. Implications for the authors' past modeling of task-switching performance are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of familiarization on alertness and encoding in children.

Three experiments with a total of 56 1st graders explored a theoretical interpretation of stimulus familiarization, the finding that after repeated exposure to a stimulus, reaction time is slower to that stimulus than to a novel one. In Exp I, this phenomenon was replicated. Exp II and Exp III, using a reaction time paradigm analogous to one that separates attention into alertness and encoding components, demonstrated that (a) the familiarization effect results primarily from a decrease in alertness associated with a familiar stimulus and (b) when alertness is held constant, reaction time to the familiar stimulus is faster than reaction time to the novel stimulus due to an encoding advantage enjoyed by the familiar stimulus. Developmental implications of an overall processing system are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of encoding task on age-related differences in the functional neuroanatomy of face memory.

Age-related differences in brain activity mediating face recognition were examined using positron emission tomography. Participants encoded faces using a pleasant-unpleasant judgement, a right-left orientation task, and intentional learning. Scans also were obtained during recognition. Both young and old groups showed significant effects of encoding task on recognition accuracy, but older adults showed reduced accuracy overall. Increased brain activity in older adults was similar to that seen in young adults during conditions associated with deeper processing, but was reduced during the shallow encoding and recognition conditions. Differential correlations of brain activity and behavior were found that suggest older adults use unique neural systems to facilitate face memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Encoding pictures in scene contexts: Does task demand influence effects of encoding congruity?

Three experiments examined the role of task demand in accounting for the effect of encoding congruity in levels-of-processing research. The effect of encoding congruity refers to the likelihood of remembering items associated with yes responses better than items associated with no responses. Ss made yes responses if target pictures were congruous with prior scene contexts or if targets and prior contexts were incongruous. Congruous contexts yielded better incidental cued recall and name recognition than incongruous ones, independently of response type. However, effects of encoding congruity and response type were not significant for picture recognition. It is suggested that the effect of encoding congruity depends on the ability to integrate target items into consistent contexts. However, encoding congruity facilitates remembering pictures' identity, but not their visual details. The relevance of the results to scene schema research is also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive decline in old age: Separating retest effects from the effects of growing older.

Repeated administration of cognitive tests improves test performance, making it difficult for researchers to gauge the true extent of age-related cognitive decline. The authors examined this issue using data from the Rush Religious Orders Study and linear mixed-effects models. At annual intervals for up to 8 years, more than 800 older Catholic clergy members completed the same set of 19 cognitive tests from which previously established composite measures of cognitive domains were derived. Retest effects on some measures were substantial and continued to accumulate even after 8 annual test readministrations, but effects on other measures were minimal. Across cognitive measures, retest effects were not related to age, sex, or education. Individual differences in retest effects were substantial but not consistent across cognitive measures. The results suggest that retest-based improvement in cognitive test performance can be substantial and persistent. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of task complexity on contextual interference in a drawing task

A large number of studies demonstrated the beneficial effects of contextual interference (CI) created by a random practice of different task variations during training on the retention and transfer of motor skills. Current interpretations of this phenomenon assume that random practice engages the subjects in deep and elaborate processing of movement related information, whereas blocked practice results in more superficial processing leading to poorer performance on later retention and transfer tests. According to this line of interpretation, we hypothesised that the complexity of the task to be learned could modulate the effects of CI. If the task is sufficiently complex, it could force the subjects to rely on such elaborate processing, and the beneficial effects of the intertask interference created by random practice could be obscured in that case. We tested this hypothesis by analysing the effects of practice schedule (random vs. blocked), on the acquisition, retention and transfer of learning in a drawing task where subjects had to reproduce accurately, without visual control, geometrical patterns presented on a video screen, as a function of task complexity defined by the number of segments (two, three or four) of each pattern. The results indicated a clear beneficial effect of random over blocked practice on delayed retention and transfer. However, this CI effect was only observed in subjects who learned the simplest movements, and was not observed in subjects who practised the more complex task. These results are discussed in terms of intratask interference created by the planning of multiple movements and the processing of knowledge of results (KR) when the number of drawing movements is increased. These findings support the assumption that the level of cognitive effort in which the subjects are engaged during training is a main factor influencing long-term retention and transfer of motor skills.     

Utterance format effects phonological priming in the picture-word task: Implications for models of phonological encoding in speech production.

Picture-word experiments investigating the production of multiword utterances with distractors that are phonologically related to words in noninitial position have yielded inconsistent results, ranging from facilitation to inhibition. A comparison of these studies is complicated by differences in detail. In parallel to the empirical inconsistencies, different theoretical accounts of phonological encoding in speech production have been provided. In the present article, the authors propose a unitary account, which can in principle account for facilitation, null effects, and inhibition. It assumes a graded activation pattern of the elements within the scope of phonological advance planning. The account is tested in an experiment varying utterance format while keeping all other aspects constant. The results are consistent with the proposed unitary account. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Separating mnemonic process from participant and item effects in the assessment of ROC asymmetries.

One of the most influential findings in the study of recognition memory is that receiver operating characteristic (ROC) curves are asymmetric about the negative diagonal. This result has led to the rejection of the equal-variance signal detection model of recognition memory and has provided motivation for more complex models, such as the unequal-variance signal detection and dual-process models. Here, the authors test the possibility that previous demonstrations of ROC asymmetry do not reflect mnemonic process but rather reflect distortions due to averaging data over items. Application of a hierarchical unequal-variance signal detection model reveals that asymmetries are in fact a real phenomenon and do not reflect distortions from averaging data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Verb-specific constraints in sentence processing: Separating effects of lexical preference from garden-paths.

Immediate effects of verb-specific syntactic (subcategorization) information were found in a cross-modal naming experiment, a self-paced reading experiment, and an experiment in which eye movements were monitored. In the reading studies, syntactic misanalysis effects in sentence complements (e.g., "The student forgot the solution was…") occurred at the verb in the complement (e.g., was) for matrix verbs typically used with noun phrase complements but not for verbs typically used with sentence complements. In addition, a complementizer effect for sentence-complement-biased verbs was not due to syntactic misanalysis but was correlated with how strongly a particular verb prefers to be followed by the complementizer that. The results support models that make immediate use of lexically specific constraints, especially constraint-based models, but are problematic for lexical filtering models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interactive effects of extraversion and arousal on attentional task performance: Multiple resources or encoding processes?

Reports study of the effects on 6 tasks of time of day, extraversion, and self-report arousal. We selected tasks to test processing resource explanations of interactive effects of extraversion and arousal on performance. Significant interactive effects of time of day, extraversion, and arousal on performance consistent with previous research were found with 2 tasks. One of these tasks was attentional (speed of serial reaction), the other required short-term memory (digit span). The interactions we found do not support the common assumption that effects of extraversion on performance are mediated by arousal. Also, the task specificity of the Extraversion?×?Arousal interactions is inconsistent with existing processing resource theories of personality. An alternative hypothesis, which resolves these difficulties, is that time of day, extraversion, and arousal interactively affect stimulus encoding at an early stage of analysis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cholinergic drug effects on a delayed conditional discrimination task in the rat

The centrally acting cholinergic antagonist scopolamine (0.025-0.10 mg/kg ip) and the peripherally acting cholinergic antagonist methyl-scopolamine (0.01-0.10 mg/kg) dose dependently impaired discriminability independent of delay in a delayed conditional discrimination task that precludes use of mediating behavior. This indicates that scopolamine does not specifically affect working memory. Drugs that enhance cholinergic transmission neither improved discriminability nor attenuated scopolamine-induced impairments. In a post hoc analysis scopolamine was found to impair discriminability in a delay-dependent manner in rats that performed at a high level in pretest sessions. Methyl-scopolamine impaired performance independently of delay in these rats. The authors suggest that a ceiling effect at short delays produced this Drug x Delay interaction of scopolamine in the best performing rats.     

Modeling the effects of hypoglycemia on a two-choice task in adult humans.

Objective: Previous research has demonstrated that hypoglycemia causes reaction times to be slower and more variable. Reaction time tests, however, use multiple cognitive and noncognitive processes. This study is the first to use a validated sequential sampling model (diffusion model) applied to results obtained from a simple 2-choice task in adult humans to assess the effects of hypoglycemia on the basic parameters of decision making. Method: Fourteen adult volunteers were tested on a numerosity discrimination task with and without reduced blood glucose concentrations. The results were analyzed with a model that dissects the components of processing that underlie decisions: the quality of the information on which a decision is based (drift rate), the critical amount of evidence that must be accumulated before a decision is made (boundary separation), and the time taken by nondecision processes. Results: Hypoglycemia resulted in a reduction of mean drift rate from 0.290 to 0.211, t(13) = 4.10, p     

The effects of inverting natural stimuli in a flanker task.

The flanker task developed by B. A. Eriksen and C. W. Eriksen (1974) is a reliable method of showing the effect of flanking stimuli (flankers) on responses to central targets. When flankers map to the same or different responses as the targets, response latencies reduce or increase, respectively, relative to neutral flankers. In Experiment 1, the authors present 2-dimensional line drawings of structurally distinct animals: 2 birds, 2 bugs, and 2 dogs. These pairs generated a reliable flanker compatibility effect (FCE) for both upright and inverted flankers. In Experiment 2, the authors present pairs of structurally similar animals: 2 dogs, 2 cows, and 2 horses. These produced a reliable FCE for only upright flankers. The results are discussed in line with structural categorisation of stimuli being invariant of object orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting duration of sleep from the three process model of regulation of alertness

OBJECTIVES: Irregular working hours severely disturb sleep and wakefulness. This paper presents a modification of the quantitative (computerised) three process model of regulation of alertness to predict duration of sleep in connection with irregular sleep patterns. METHODS: The model uses a circadian "C" (sinusoidal) and homeostatic "S" (exponential) component (the duration of previous periods awake and asleep), which are summed to yield predicted alertness (on a scale of 1-16). It assumes that waking from sleep will occur at a given alertness level (S' + C') when recuperation is complete. Variables of electroencephalographic duration of sleep from two studies of irregular sleep were used to model the S and C variables in a regression approach to maximise prediction. The model performance was cross validated against published field and laboratory data. RESULTS: The model parameters were defined with a high degree of precision R2 = 0.99 and the validation yielded similar values R2 = 0.98-0.95, depending on the acrophase. The paper also describes a simplified graphical version of the computation model seen as a two dimensional duration of sleep nomogram. CONCLUSION: The model seems to predict group means for duration of sleep with high precision and may serve as a tool for evaluating work and rest schedules to reduce risks of sleep disturbances.     

Recency effects as a window to generalization: Separating decisional and perceptual sequential effects in category learning.

Accounts of learning and generalization typically focus on factors related to lasting changes in representation (i.e., long-term memory). The authors present evidence that shorter term effects also play a critical role in determining performance and that these recency effects can be subdivided into perceptual and decisional components. Experimental results based on a probabilistic category structure show that the previous stimulus exerts a contrastive effect on the current percept (perceptual recency) and that responses are biased toward or away from the previous feedback, depending on the similarity between successive stimuli (decisional recency). A method for assessing these recency effects is presented that clarifies open questions regarding stimulus generalization and perceptual contrast effects in categorization and in other domains. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of age and a divided attention task presented during encoding and retrieval on memory.

The present studies were designed to examine age differences in memory when attention was divided during encoding, retrieval, or at both times. In Experiment 1, Ss studied categorized words while performing a number-monitoring task during encoding, retrieval, or at both times. Older Ss' free recall and clustering performance declined more than that of young Ss when attention was divided at encoding, but there was no similar age interaction when divided attention occurred at retrieval. In Experiment 2, the task demands at retrieval were increased by using a fast-paced, cued-recall task. The results remained unchanged from Experiment 1. Again, an age interaction occurred with divided attention at encoding but not at retrieval. These results were unexpected, given the emphasis in the memory-aging literature on increased difficulty of retrieval by older adults. The findings pose difficulties for limited processing resource views of age differences in memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Updating knowledge about encoding strategies: A componential analysis of learning about strategy effectiveness from task experience.

Researchers have argued for age deficits in learning about the effects of encoding strategies from task experience, partly on the basis of absolute accuracy of metacognitive judgments. However, these findings could be attributed to factors other than age differences in learning. Forty older and 40 younger adults participated in 2 study-test trials in which they studied paired associates with imagery or repetition, predicted recall for the items, attempted recall, and postdicted recall. Recall was greater after imagery than repetition, yet this effect was not fully reflected by predictions made on Trial 1. Although both older and younger adults accurately postdicted recall from Trial 1, absolute accuracy of the predictions made on Trial 2 showed little improvement. By contrast, both age groups demonstrated increases in between-person correlations of predictions with recall, which is inconsistent with age deficits in knowledge updating. Thus, both older and younger adults had updated knowledge about the relative effects of the strategies, but such updating was not evident in the absolute accuracy of the predictions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Masked priming effects with syllabic neighbors in a lexical decision task.

Four lexical decision experiments using a masked priming paradigm were conducted to analyze whether the previous presentation of a syllabic neighbor (a word sharing the same 1st syllable) influences recognition performance. The results showed an inhibitory effect of more frequent syllabic primes and some facilitation of nonword syllabic primes (Experiments 1-3). When monosyllabic pairs were used (Experiment 3), no priming effects of the 2 initial letters were found. Finally, when using only syllables as primes, latencies to words were shorter when preceded by primes that corresponded to the 1st syllable than by primes that contained 1 letter more or less than the lst syllable (Experiment 4). Results are interpreted using activation models that take into account a syllabic level of representation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial compatibility effects with Hemifield presentation in a unimanual two-finger task.

A unimanual, 2-finger choice RT task was used in conjunction with visual signals presented to either the left or right visual field of 16 right-handed undergraduates. Spatial compatibility effects were noted. Responses were quicker for right-field presentations when the rightmost fingers of either hand made the response, and for the left-field presentation when the leftmost finger responded. This compatibility was observed for easy but not difficult decisions on both perceptually and symbolically based choice tasks. The magnitude of the compatibility effect did not differ as a function of which hand made the response. (French abstract) (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)