Insensitivity of visual short-term memory to irrelevant visual information

Several authors have hypothesised that visuo-spatial working memory is functionally analogous to verbal working memory. Irrelevant background speech impairs verbal short-term memory. We investigated whether irrelevant visual information has an analogous effect on visual short-term memory, using a dynamic visual noise (DVN) technique known to disrupt visual imagery (Quinn & McConnell, 1996a). Experiment 1 replicated the effect of DVN on pegword imagery. Experiments 2 and 3 showed no effect of DVN on recall of static matrix patterns, despite a significant effect of a concurrent spatial tapping task. Experiment 4 showed no effect of DVN on encoding or maintenance of arrays of matrix patterns, despite testing memory by a recognition procedure to encourage visual rather than spatial processing. Serial position curves showed a one-item recency effect typical of visual short-term memory. Experiment 5 showed no effect of DVN on short-term recognition of Chinese characters, despite effects of visual similarity and a concurrent colour memory task that confirmed visual processing of the characters. We conclude that irrelevant visual noise does not impair visual short-term memory. Visual working memory may not be functionally analogous to verbal working memory, and different cognitive processes may underlie visual short-term memory and visual imagery

Changes in the capacity of visual working memory in 5- to 10-year-olds

Using the Luck and Vogel change detection paradigm, we sought to investigate the capacity of visual working memory in 5-, 7-, and 10-year-olds. We found that performance on the task improved significantly with age and also obtained evidence that the capacity of visual working memory approximately doubles between 5 and 10 years of age, where it reaches adult levels of approximately three to four items

Visuospatial tasks suppress craving for cigarettes.

The Elaborated Intrusion (EI) theory of desire posits that visual imagery plays a key role in craving. We report a series of experiments testing this hypothesis in a drug addiction context. Experiment 1 showed that a mental visual imagery task with neutral content reduced cigarette craving in abstaining smokers, but that an equivalent auditory task did not. The effect of visual imagery was replicated in Experiment 2, which also showed comparable effects of non-imagery visual working memory interference. Experiment 3 showed that the benefit of visual over auditory interference was not dependent upon imagery being used to induce craving. Experiment 4 compared a visuomotor task, making shapes from modeling clay, with a verbal task (counting back from 100), and again showed a benefit of the visual over the non-visual task. We conclude that visual imagery supports craving for cigarettes. Competing imagery or visual working memory tasks may help tackle craving in smokers trying to quit

Relationships between working memory, expressive vocabulary and arithmetical reasoning in children with and without intellectual disabilities.

This experiment examined the relationships between working memory and two measures of achievement, namely expressive vocabulary and arithmetical reasoning, in children with and without intellectual disabilities (ID). For 11-12-year-old children with intellectual disabilities, memory measures tapping the central executive were the most important predictors of both expressive vocabulary and arithmetical reasoning, with phonological memory making a small additional contribution to expressive vocabulary. For mainstream 11-12-year-old children, phonological memory was the best predictor of expressive vocabulary, whereas, arithmetical reasoning ability was predicted by visual memory and to a lesser extent phonological memory. The third group of children, 7-8-year-old mainstream children, had been matched on mental age with the intellectual disability group. For these children the most important predictor of expressive vocabulary was phonological memory, with a small additional contribution from visual memory. Arithmetical reasoning was best predicted by memory measures tapping the central executive with an additional contribution from phonological memory. These results suggest that different working memory resources are used by children of varying ages and ability levels to carry out at least some cognitive tasks

F211. Finding and fixing attentional dysfunction in schizophrenia

BACKGROUND Schizophrenia is the most debilitating health problem that exists, and its cognitive impairments are the greatest predictor of disability. Since the earliest clinical descriptions of the illness, abnormalities of attention have been at the core of the cognitive symptoms of schizophrenia. Theories of attentional dysfunction in schizophrenia propose that the deficits arise from either an inability to maintain working memory representations that guide attention, or difficulty focusing lower-level visual attention mechanisms. However, these theoretical accounts neglect the role of long-term memory representations in controlling attention. METHODS To test competing accounts of the etiology of cognitive deficits in schizophrenia, we devised a cued visual search task that allowed us to examine the integrity of the memory mechanisms that control attention and the lower-level mechanisms for focusing attention on visual inputs in patients with schizophrenia and demographically matched controls. In this task, a target object was cued at the beginning of each trial. The task-relevant cue signaled the identity of the target that could appear in the search array presented a second later. Then the target remained the same for three to seven consecutive trials (length of run randomized) before it was changed to a different object. While patients and controls were repeatedly searching for the same target object, we used electrophysiological measurements of brain activity to directly measure how they were focusing attention on the search targets, as well as how they recruited working memory and long-term memory representations to control attention as they searched for the task-relevant targets. In a second experiment, we used a causal manipulation of brain activity to provide converging evidence for our hypotheses regarding the locus of the attentional deficits in schizophrenia and to determine whether it is possible to improve attention in patients. This experiment was a double-blind, sham-controlled, within-subjects design using transcranial direct-current stimulation (tDCS) and established electroencephalographic (EEG) signatures of working memory, long-term memory, and attention. RESULTS Here, we show that the control of perceptual attention is impaired in people with schizophrenia, and that this impairment is driven by an inability to shift attentional control from working memory to long-term memory across practice. Contrary to predictions of the dominant models, this attentional impairment is observed in the face of exuberant neural activity indexing working memory and completely normal activity indexing the focusing of visual attention. Next, we provide converging evidence for the locus of attentional impairments in long-term memory by showing that noninvasive electrical stimulation of medial frontal cortex rectifies long-term memory related neural signatures and normalizes the ability of patients to find targets in complex visual scenes. DISCUSSION The findings challenge existing views of the locus of dysfunction underlying attentional impairments in schizophrenia. Moreover, the results highlight the crucial importance of long-term memory systems in controlling attention and associated abnormalities in the hippocampus and other brain areas in schizophrenia.Published versio

Controlling attention to nociceptive stimuli with working memory

Background: Because pain often signals the occurrence of potential tissue damage, a nociceptive stimulus has the capacity to involuntarily capture attention and take priority over other sensory inputs. Whether distraction by nociception actually occurs may depend upon the cognitive characteristics of the ongoing activities. The present study tested the role of working memory in controlling the attentional capture by nociception. Methodology and Principal Findings: Participants performed visual discrimination and matching tasks in which visual targets were shortly preceded by a tactile distracter. The two tasks were chosen because of the different effects the involvement of working memory produces on performance, in order to dissociate the specific role of working memory in the control of attention from the effect of general resource demands. Occasionally (i.e. 17% of the trials), tactile distracters were replaced by a novel nociceptive stimulus in order to distract participants from the visual tasks. Indeed, in the control conditions (no working memory), reaction times to visual targets were increased when the target was preceded by a novel nociceptive distracter as compared to the target preceded by a frequent tactile distracter, suggesting attentional capture by the novel nociceptive stimulus. However, when the task required an active rehearsal of the visual target in working memory, the novel nociceptive stimulus no longer induced a lengthening of reaction times to visual targets, indicating a reduction of the distraction produced by the novel nociceptive stimulus. This effect was independent of the overall task demands. Conclusion and Significance: Loading working memory with pain-unrelated information may reduce the ability of nociceptive input to involuntarily capture attention, and shields cognitive processing from nociceptive distraction. An efficient control of attention over pain is best guaranteed by the ability to maintain active goal priorities during achievement of cognitive activities and to keep pain-related information out of task settings

The cognitive neuroscience of visual working memory

Visual working memory allows us to temporarily maintain and manipulate visual information in order to solve a task. The study of the brain mechanisms underlying this function began more than half a century ago, with Scoville and Milner’s (1957) seminal discoveries with amnesic patients. This timely collection of papers brings together diverse perspectives on the cognitive neuroscience of visual working memory from multiple fields that have traditionally been fairly disjointed: human neuroimaging, electrophysiological, behavioural and animal lesion studies, investigating both the developing and the adult brain

Attentional demand influences strategies for encoding into visual working memory

Visual selective attention and visual working memory (WM) share the same capacity-limited resources. We investigated whether and how participants can cope with a task in which these 2 mechanisms interfere. The task required participants to scan an array of 9 objects in order to select the target locations and to encode the items presented at these locations into WM (1 to 5 shapes). Determination of the target locations required either few attentional resources (“popout condition”) or an attention-demanding serial search (“non pop-out condition”). Participants were able to achieve high memory performance in all stimulation conditions but, in the non popout conditions, this came at the cost of additional processing time. Both empirical evidence and subjective reports suggest that participants invested the additional time in memorizing the locations of all target objects prior to the encoding of their shapes into WM. Thus, they seemed to be unable to interleave the steps of search with those of encoding. We propose that the memory for target locations substitutes for perceptual pop-out and thus may be the key component that allows for flexible coping with the common processing limitations of visual WM and attention. The findings have implications for understanding how we cope with real-life situations in which the demands on visual attention and WM occur simultaneously. Keywords: attention, working memory, interference, encoding strategie

How conscious experience and working memory interact

Active components of classical working memory are conscious, but traditional theory does not account for this fact. Global Workspace theory suggests that consciousness is needed to recruit unconscious specialized networks that carry out detailed working memory functions. The IDA model provides a fine-grained analysis of this process, specifically of two classical workingmemory tasks, verbal rehearsal and the utilization of a visual image. In the process, new light is shed on the interactions between conscious and unconscious\ud aspects of working memory

The Contralateral Delay Activity Tracks the Sequential Loading of Objects into Visual Working Memory, Unlike Lateralized Alpha Oscillations

Visual working memory temporarily represents a continuous stream of task-relevant objects as we move through our environment performing tasks. Previous work has identified candidate neural mechanisms of visual working memory storage; however, we do not know which of these mechanisms enable the storage of objects as we sequentially encounter them in our environment. Here, we measured the contralateral delay activity (CDA) and lateralized alpha oscillations as human subjects were shown a series of objects that they needed to remember. The amplitude of CDA increased following the presentation of each to-be-remembered object, reaching asymptote at about three to four objects. In contrast, the concurrently measured lateralized alpha power remained constant with each additional object. Our results suggest that the CDA indexes the storage of objects in visual working memory, whereas lateralized alpha suppression indexes the focusing of attention on the to-be-remembered objects