The role of the human thalamus in language and memory: evidence from electrophysiological studies

The data reviewed here indicate that electrical stimulation of the dominant ventrolateral thalamus can produce deficits in language processing that are not seen after similar stimulation of the nondominant ventrolateral thalamus. The nature of the language deficit produced varies, depending upon the rostrocaudal location of the stimulation site. Stimulation of the anterior left ventrolateral thalamus in right-handed patients resulted in production of a repeated erroneous word, stimulation of the medial ventrolateral thalamus evoked perseveration, and stimulation of the posterior ventrolateral thalamus and anterior pulvinar resulted in misnaming and omissions. Additional studies have examined the effect of electrical thalamic stimulation on verbal and nonverbal short-term memory. Left (but not right) ventrolateral thalamic stimulation during verbal memory input greatly decreased subsequent recall errors, while stimulation during verbal memory retrieval increased recall errors. This finding contrasted with those obtained from studies on nonverbal memory, in which right ventrolateral stimulation during memory input decreased recall errors, while left thalamic stimulation at the same stage increased recall errors. Left pulvinar stimulation disrupted verbal memory processing, while right pulvinar stimulation disrupted nonverbal memory processing. Limited evidence suggests that the effects of thalamic electrical stimulation on verbal memory may persist for several days after the stimulation has ended. The lateralization of thalamic functions also affects the motoric aspects of speech production. Left (but not right) ventrolateral thalamic stimulation disrupted speech articulation and increased the expiratory phase of respiration. The fact that these motor effects were evoked from the same general area of the thalamus that produced the language deficits discussed above raises the possibility that the thalamus is involved in coordinating the cognitive and motoric aspects of language production. A model of thalamic function is discussed in which defined regions of the thalamus operate as a "specific alerting response," increasing the input to memory of category-specific material while simultaneously inhibiting retrieval from memory.     

The mere exposure effect is sensitive to color information: evidence for color effects in a perceptual implicit memory test

Priming effects in perceptual tests of implicit memory are assumed to be perceptually specific. Surprisingly, changing object colors from study to test did not diminish priming in most previous studies. However, these studies used implicit tests that are based on object identification, which mainly depends on the analysis of the object shape and therefore operates color-independently. The present study shows that color effects can be found in perceptual implicit tests when the test task requires the processing of color information. In Experiment 1, reliable color priming was found in a mere exposure design (preference test). In Experiment 2, the preference test was contrasted with a conceptually driven color-choice test. Altering the shape of object from study to test resulted in significant priming in the color-choice test but eliminated priming in the preference test. Preference judgments thus largely depend on perceptual processes. In Experiment 3, the preference and the color-choice test were studied under explicit test instructions. Differences in reaction times between the implicit and the explicit test suggest that the implicit test results were not an artifact of explicit retrieval attempts. In contrast with previous assumptions, it is therefore concluded that color is part of the representation that mediates perceptual priming.     

Q-Coh: A tool to screen the methodological quality of cohort studies in systematic reviews and meta-analyses

The evaluation of the methodological quality of primary studies in a systematic review is a key process to enhance the likelihood of achieving valid results. When considering non-randomized designs as cohort studies, this process becomes even more critical, since these designs are more susceptible to bias than randomized controlled trials are. Taking this into account, a tool, named Q-Coh, was designed with the aim to screen the methodological quality of the primary studies with a cohort design priming specificity over sensitivity in a reasonable application time. After applying it to 21 prospective cohort studies by three raters, all domains had a moderate to good agreement, with all except one of them having statistically significant kappa values. Despite there is no gold standard for the methodological quality, arguments supporting its validity are given. Future research should assess the psychometric properties of Q-Coh in the context of real meta-analyses, evaluate the influence of the raters’ substantive and methodological expertise on these properties, and explore different ways of including the domains-based ratings of the quality provided by Q-Coh into meta-analyses.     

The origins of levels-of-processing effects in a conceptual test: evidence for automatic influences of memory from the process-dissociation procedure

In three experiments, we explored automatic influences of memory in a conceptual memory task, as affected by a levels-of-processing (LoP) manipulation. We also explored the origins of the LoP effect by examining whether the effect emerged only when participants in the shallow condition truncated the perceptual processing (the lexical-processing hypothesis) or even when the entire word was encoded in this condition (the conceptual-processing hypothesis). Using the process-dissociation procedure and an implicit association-generation task, we found that the deep encoding condition yielded higher estimates of automatic influences than the shallow condition. In support of the conceptual processing hypothesis, the LoP effect was found even when the shallow task did not lead to truncated processing of the lexical units. We suggest that encoding for meaning is a prerequisite for automatic processing on conceptual tests of memory.     

Self-Handicapping in the Classroom: The Effects of Claimed Self-Handicaps on Responses to Academic Failure

The hypothesis that self-handicapping is in the service of self-esteem protection was examined in a naturalistic setting. College students were assessed for individual differences in self-handicapping and attributional style at the beginning of the term. Prior to the first exam they had an opportunity to claim handicaps that might hamper their performance on the exam. After receiving feedback that they had performed poorly on the exam, all students completed measures of mood, self-esteem, and performance attributions. Support for the hypothesis was found for men but not for women. Level of self-handicapping interacted with sex of subject such that high self handicapping among men predicted claimed handicapping prior to the exam and more external attributions for poor performance and higher self-esteem following feedback. Among women, the relations between self-handicapping tendencies and claimed handicaps and performance attributions were weaker than for men. In addition, unlike men's, women's post feedback self-esteem was unrelated to claimed handicaps and performance attributions. Potential mechanisms underlying sex differences in self-handicapping and responses to negative feedback are discussed.     

The role of stressful events in the relationship between positive and negative affects: evidence from field and experimental studies

Three studies are presented that examine the effects of stress on the relationship between positive and negative affective states. In the first study, recently bereaved and disabled older adults were compared to matched control groups without these recent stressors. Negative affect was inversely correlated with positive affect to a significantly greater extent for the highly stressed groups compared with controls. In a second study, older adults were exposed to a laboratory stressor, and their positive and negative affective reactions recorded. Immediately following a speech stressor task, the inverse correlation between positive and negative affect was significantly greater than in pre- and postassessments of affects. The third study was an attempt to replicate and extend the findings from Study 2 with a mid-aged sample of women. The speech stressor had the same effects as in Study 2. A second stressor, which induced pain through immersion of an arm into cold water, had no effects on the correlation between affective states. Alternative explanations for these effects and the implications for cognitive interventions are discussed.     

The psychology of psychiatric genetics: evidence that positive emotions in females moderate genetic sensitivity to social stress associated with the BDNF Val-sup-6-sup-6Met polymorphism

Previous work indicated protective effects of positive emotions on genetically influenced stress sensitivity. Given the fact that expression of brain-derived-neurotrophic-factor (BDNF) is associated with stress-induced behavioral changes, it was hypothesized that the BDNF Val-sup-6-sup-6Met genotype may mediate genetic effects on stress sensitivity, conditional on the level of concurrent positive emotions. Subjects (n=446) participated in a momentary assessment study, collecting appraisals of stress and affect in the flow of daily life. Multilevel regression analyses examined moderation of daily life stress-induced negative affect (NA) by BDNF genotype, and to what degree this was conditional on concurrent positive emotions. Results showed that heterozygous BDNF "Met" carriers exhibited an increased NA response to social stress compared with "Val/Val" subjects. Positive emotions at the time of the stressor decreased BDNF genetic moderation of the NA response to social stress in a dose-response fashion. This effect was most pronounced in BDNF Met carriers. Thus, the impact of BDNF genotype on stress sensitivity is conditional on the experience of positive emotions. Interdisciplinary research in psychology and psychiatric genetics may lead to the improvement of treatment choices in stress-related disorders.     

The mapping from sound structure to the lexicon in aphasia: evidence from rhyme and repetition priming

Two studies were conducted to explore the hypothesis that Broca's and Wernicke's aphasics have deficits arising from the processes involved in activating the lexicon from phonological form. The first study explored whether phonologically similar lexical entries differing only in their initial consonants show "rhyme priming." Results revealed that Broca's aphasics failed to show facilitation when the target was identical to the prime (i.e. identity priming) and they showed significant inhibition when targets were preceded by rhyming words. Wernicke's aphasics showed a pattern of results similar to that of normal subjects, i.e., identity priming and rhyme priming as well as significantly slower reaction-times in the rhyming condition compared to the identity condition. The second study investigated form-based repetition priming in aphasic patients at a number of intervals including when no other stimuli intervened between repeated stimuli (0 lag) or when 4, 8, or 12 stimuli intervened. Results showed that, unlike old normal subjects who showed repetition priming for both words and nonwords, both Broca's and Wernicke's aphasics showed repetition priming for word targets only. Moreover, in contrast to old normal subjects who showed a greater magnitude of priming at 0 lag for word targets, neither Broca's aphasics or Wernicke's aphasics showed priming at 0 lag. Implications of these findings are considered with respect to the hypotheses that Broca's and Wernicke's aphasics have deficits in the nature of the activation patterns within the lexicon itself and in auditory (working) memory.     

Drawing out resistance: The use of the house-tree-person test to facilitate communication in verbal therapy groups

Resistance as an impediment in both individual and group therapy is discussed, and the special resistances common to groups are described through a review of the literature. An adaptation of John Buck's House-Tree-Person projective test is suggested as a method for overcoming resistance that can be used by group therapists, including those unfamiliar with art therapy techniques. Case examples are presented of a group session in which resistance is a prominent deterrent to progress and another in which the use of the projective drawing technique facilitates the dissolution of resistance.     

Expectancy confirmation in spite of disconfirming evidence: The case of price increases due to the introduction of the Euro

People in Germany overwhelmingly believe that the Euro introduction caused an overall price increase, however, no such increase actually took place. To investigate whether this disparity could be based on biased perceptions of the average price trend, four studies were conducted. Participants received two menus from a restaurant (one ‘old’ menu with German Mark (DM) prices and one ‘new’ menu with Euro prices) and were asked to estimate the price trend (in per cent). In all of these studies, price trend judgements were biased towards rising prices. If the prices had in fact been raised, the magnitude of this price increase was overestimated. If the prices had remained stable, significant price increases were perceived. And if the prices had fallen, they were perceived as having remained stable. The bias was systematically related to participants' expectations concerning price increases. A ‘selective outcome correction’ hypothesis proved to best fit the data: incorrect calculation outcomes that are in line with one's expectations are overlooked, whereas incorrect inconsistent outcomes are detected and corrected. The results imply that expectations can influence judgements even when clear disconfirming evidence is available that can be compared with an objective standard, thus leaving no room for interpretation. Copyright © 2004 John Wiley & Sons, Ltd.     

The crucial importance of empirical evidence in the development of bereavement theory: reply to Archer (2001).

In his commentary, J. Archer (2001a) argued that G. A. Bonanno and S. Kaltman's (1999) review and integration of the bereavement literature failed to consider evolutionary theory or other approaches to the origins of grief. Archer also argued that Bonanno and Kaltman had merely replaced the traditional grief work perspective with cognitive restructuring, thereby ignoring the processes related to avoidance and distancing from the loss. In this reply, the author first explains that although it was compelling to do so, Bonanno and Kaltman did not emphasize an evolutionary approach to the origins of grief reactions because in their current form these theories lack empirical and theoretical clarity. Second, the author shows that, contrary to Archer's reading, Bonanno and Kaltman's article viewed cognitive restructuring as a mechanism used primarily by extremely grieved persons and only in some cognitive domains. Last, the author shows that Bonanno and Kaltman have championed rather than ignored avoidant or distancing processes.     

The representation of instructions in working memory leads to autonomous response activation: evidence from the first trials in the flanker paradigm

The authors examined whether instructions can lead to autonomous response activation even without practice. Eriksen and Eriksen's (1974) flanker compatibility paradigm was used to show that the flanker compatibility effect (FCE) is already present in the first trials following the stimulus-response instructions, before any of the stimuli have been repeated. This first-trials FCE was present even when participants were strongly motivated to ignore the flankers, and it disappeared under conditions of high working-memory (WM) load. The findings suggest that intention, formed by instructions, is involved in forming representations in WM that operate like a prepared reflex (Woodworth, 1938). The implications of the finding to intentionality and frontal lobe functions are discussed.     

On the "optimal" size for normative samples in neuropsychology: capturing the uncertainty when normative data are used to quantify the standing of a neuropsychological test score.

Bridges and Holler (2007) have provided a useful reminder that normative data are fallible. Unfortunately, however, their paper misleads neuropsychologists as to the nature and extent of the problem. We show that the uncertainty attached to the estimated z score and percentile rank of a given raw score is much larger than they report and that it varies as a function of the extremity of the raw score. Methods for quantifying the uncertainty associated with normative data are described and used to illustrate the issues involved. A computer program is provided that, on entry of a normative sample mean, standard deviation, and sample size, provides point and interval estimates of percentiles and z scores for raw scores referred to these normative data. The methods and program provide neuropsychologists with a means of evaluating the adequacy of existing norms and will be useful for those planning normative studies.     

The time course of access to semantic information in high-performing older adults: behavioral evidence for the hemispheric asymmetry reduction in OLDer individuals

The possibility that the HAROLD phenomenon (i.e., Hemispheric Asymmetry Reduction in OLDer adults) is manifested in the course of access to semantic information, in particular the meaning of emotional words, was investigated using the visual half-field priming paradigm. The time course of priming was tracked in the cerebral hemispheres across three SOAs: 150, 300, and 750 ms. The results showed older and young adults had the same level of accuracy. While priming occurred unilaterally in young participants, the pattern of priming in older participants appeared to be bilateral whenever it was present, that is, at the 300- and 750-ms SOAs. The delay in the appearance of priming in older adults may be due to an increase in sensory thresholds that causes older adults to need more time to encode stimuli and fully activate their semantic network. It is concluded that the bilateral pattern of priming in the presence of an equivalent level of performance in older adults provides behavioral evidence supporting the compensatory role of the HAROLD phenomenon for this particular task.