Dual representation of item positions in verbal short-term memory: Evidence for two access modes

Memory sets of N=1 ~ 5 digits were exposed sequentially from left-to-right across the screen, followed by N recognition probes. Probes had to be compared to memory list items on identity only (Sternberg task) or conditional on list position. Positions were probed randomly or in left-to-right order. Search functions related probe response times to set size. Random probing led to ramped, “Sternbergian” functions whose intercepts were elevated by the location requirement. Sequential probing led to flat search functions—fast responses unaffected by set size. These results suggested that items in STM could be accessed either by a slow search-on-identity followed by recovery of an associated location tag, or in a single step by following item-to-item links in study order. It is argued that this dual coding of location information occurs spontaneously at study, and that either code can be utilised at retrieval depending on test demands.     

Forgetting of prior remembering in persons reporting recovered memories of childhood sexual abuse

Case studies of individuals reporting recovered memories of childhood sexual abuse suggest that some overestimate their prior forgetting of the abuse. People reporting recovered or continuous memories of childhood sexual abuse and control subjects reporting no history of abuse participated in two experiments examining this "forgot it all along" phenomenon. Participants in Experiment 1 were more likely to forget that they had previously recalled a studied item if they were cued to think of it differently on two recall tests than if they were cued to think of it in the same way on the two tests. This effect was stronger for recovered-memory participants than for continuous-memory and control participants. In Experiment 2, participants recalled autobiographical events three times over a period of 4 months. Much as in Experiment 1, they underestimated prior remembering when the events had been recalled in a different emotional frame (positive vs. negative) on the previous occasion. This underestimation was more pronounced for recovered-memory participants than for continuous-memory and control participants.     

Overwriting of phonemic features in serial recall

We tested two explanations of the phonological similarity effect in verbal short-term memory: The confusion hypothesis assumes that serial positions of similar items are confused. The overwriting hypothesis states that similar items share feature representations, which are overwritten. Participants memorised a phonologically dissimilar list of CVC-trigrams (Experiment 1) or words (Experiment 2 and 3) for serial recall. In the retention interval they read aloud other items. The material of the distractor task jointly overlapped one item of the memory list. The recall of this item was impaired, and the effect was not based on intrusions from the distractor task alone. The results provide evidence for feature overwriting as one potential mechanism contributing to the phonological similarity effect.     

Deficits of anticipatory grip force control after damage to peripheral and central sensorimotor systems

Healthy subjects adjust their grip force economically to the weight of a hand-held object. In addition, inertial loads, which arise from arm movements with the grasped object, are anticipated by parallel grip force modulations. Internal forward models have been proposed to predict the consequences of voluntary movements. Anesthesia of the fingers impairs grip force economy but the feedforward character of the grip force/load coupling is preserved. To further analyze the role of sensory input for internal forward models and to characterize the consequences of central nervous system damage for anticipatory grip force control, we measured grip force behavior in neurological patients. We tested a group of stroke patients with varying degrees of impaired fine motor control and sensory loss, a single patient with complete and permanent differentation from all tactile and proprioceptive input, and a group of patients with amyotrophic lateral sclerosis (ALS) that exclusively impairs the motor system without affecting sensory modalities. Increased grip forces were a common finding in all patients. Sensory deficits were a strong but not the only predictor of impaired grip force economy. The feedforward mode of grip force control was typically preserved in the stroke patients despite their central sensory deficits, but was severely disturbed in the patient with peripheral sensory deafferentation and in a minority of stroke patients. Moderate deficits of feedforward control were also obvious in ALS patients. Thus, the function of the internal forward model and the precision of grip force production may depend on a complex anatomical and functional network of sensory and motor structures and their interaction in time and space.     

Contextualist Approaches to Epistemology: Problems and Prospects

In this paper we survey some main arguments for and against epistemological contextualism. We distinguish and discuss various kinds of contextualism, such as attributer contextualism (the most influential version of which is semantic, conversational, or radical contextualism); indexicalism; proto-contextualism; Wittgensteinian contextualism; subject, inferential, or issue contextualism; epistemic contextualism; and virtue contextualism. Starting with a sketch of Dretskes Relevant Alternatives Theory and Nozicks Tracking Account of Knowledge, we reconstruct the history of various forms of contextualism and the ways contextualists try to handle some notorious epistemological quandaries, especially skepticism and the lottery paradox. Then we outline the most important problems that contextualist theories face, and give overviews of their criticisms and defenses as developed in this issue.     

Effects of slow-release caffeine and a nap on driving simulator performance after partial sleep deprivation

A driving simulator was used to evaluate the effectiveness of a 30-min. nap and 300-mg slow-release caffeine as countermeasures to drivers' sleepiness induced by partial sleep deprivation. 12 participants were allowed 45 hr. time in bed at the laboratory. Driving performance then was measured twice--at 9 a.m. and at 1 p.m.--by a 45-min. driving task on a simulator. Subjective sleepiness/alertness and mood were assessed four times on the Stanford Sleepiness Scale and the Profile of Mood States. Driving performance was assessed as Lane Drifting, Speed Deviation, and Accident Liability. A 30-min. nap opportunity and 300 mg of slow-release caffeine both were successful in counteracting drivers' sleepiness. The remedial effect of slow-release caffeine lasted longer than that of the nap, that is, it was also effective in the afternoon session. This suggests that slow-release caffeine represents a valuable countermeasure that, in the case of partial sleep deprivation, is preferred to a nap when sleepiness has to be counteracted for a longer time.     

Coherence Theory of Knowledge: a Gradational Account

A satisfactory theory of knowledge in which the shortcomings of a pure externalist account are avoided and in which the Gettier problem is solved should consist in a combination of externalist and internalist components. The internalist component should guarantee that the epistemic subject has cognitive access to the justifying grounds of her belief. And the externalist component should guarantee that the justification of her belief does not depend on any false statement. Keith Lehrer's coherence theory of knowledge as undefeated justification is an example of such an internalist-externalist analysis of knowledge. But nevertheless, Lehrer's account leads to unintended results. Therefore, it is argued that a satisfactory coherence theory of knowledge must also be based on a gradual notion of systematic coherence.     

Sex differences in self-reported coronary-prone factors

The FABA self-report questionnaire on coronary-prone behaviour was applied to 628 GDR subjects (343 males, 285 females), who included students, blue- and white-collar workers, and hypertensive patients, all split into three age groups (18–30, 31–50, and 51–65 years). Four scales had been previously established by factor analysis: Work Obsession (WO), Dominance/Competition (DC), Reactive Uncontrol (RU), and Need for Planning (PN). Two-tailed MANOVA and ANOVA were applied to analyse the effects of sex, age, and type of respondent (i.e. student, worker, or hypertensive) on scale means, using the defined sub-groups. No significant sex differences on WO and PN were found. With regard to DC, males of all sub-groups consistently rated themselves as more dominant and competitive than females. These differences were highly significant. RU was higher only in female students and female hypertensives. There was a significant age effect on DC and PN: the older the workers and hypertensives of both sexes, the more dominant and obsessed with planning they were. No influence of the type of respondent was apparent. Results are discussed in the light of cross-cultural research on gender differences and the particular socio-economic situation of the former GDR. © 1998 John Wiley & Sons, Ltd.     

Retrieval inhibition of trauma-related words in women reporting repressed or recovered memories of childhood sexual abuse

Several authors have argued that survivors of childhood sexual abuse (CSA) who report to have repressed their traumatic memories are more skilled in forgetting emotional stimuli than survivors who have always remembered the abuse. The current experiment employed a list-wise directed forgetting task to investigate whether women reporting repressed (n = 16) or recovered (n = 23) memories of CSA are better at forgetting disturbing material, relative to women reporting having always remembered their abuse (n = 55) or reporting no history of abuse (n = 20). We found no support for the hypothesis that women reporting repressed or recovered memories of CSA are especially versed in inhibiting retrieval of trauma-related words. Additional analyses revealed that participants characterized by a repressive coping style did not display a superior retrieval inhibition mechanism for negative material.