Left-hemisphere activation and deficient response modulation in psychopaths

Psychopathic offenders have difficulty processing contextual or secondary cues once they have initiated goal-directed behavior or allocated attention to a primary task. To test the hypothesis that this deficit in response modulation is specific to conditions in which psychopaths' left-hemisphere resources are engaged, we administered a serial recall task to 21 incarcerated psychopaths and 21 control subjects. Subjects were instructed to memorize eight words that were presented one at a time, each in one of the four corners of the visual display. Subjects' primary task was to recall the words in serial order. Then, without forewarning, they were asked to recall the words' locations. As predicted, psychopaths performed as well as control subjects in recalling words from the left and right spatial fields, but recalled significantly fewer locations from the right spatial field. Thus, psychopaths' deficient response modulation was specific to conditions in which their left-hemisphere resources were actively engaged.     

两位数的整体与局部加工

关于两位数的加工方式有整体加工说和局部加工说,实验证据主要来自数字数量控制/主动加工任务。本研究主要考察在数字数量自动加工任务中两位数的加工方式。实验一要求被试完成数量大小比较和物理大小比较两个任务,实验二只要求被试完成物理大小比较任务。结果是在数量比较任务和物理比较任务中都存在显著的个位十位一致性效应和数量物理一致性效应,这表明在两位数的数量主动和自动加工任务中均存在整体加工和局部加工两种方式。     

On the Irrelevance of Semantic Information for the llIrrelevant Speech Effect

Two experiments that tested whether semantic similarity between visually presented targets and auditorily presented distractors has an effect on serial recall of the visual targets are reported. In Experiment 1, we found no difference in the recall of two-digit numbers when distractors were either numbers or words and non-words that were designed to be phonologically similar to the targets. In Experiment 2 the 'semantic distance' between targets and distractors had no effect on serial recall. Taken together, these experiments conceptually replicate and extend earlier results, and they establish constraints for models of the effect of unattended acoustic information on serial recall.     

Holistic or compositional representation of two-digit numbers? Evidence from the distance, magnitude, and SNARC effects in a number-matching task

Whether two-digit numbers are represented holistically (each digit pair processed as one number) or compositionally (each digit pair processed separately as a decade digit and a unit digit) remains unresolved. Two experiments were conducted to examine the distance, magnitude, and SNARC effects in a number-matching task involving two-digit numbers. Forty undergraduates were asked to judge whether two two-digit numbers (presented serially in Experiment 1 and simultaneously in Experiment 2) were the same or not. Results showed that, when numbers were presented serially, unit digits did not make unique contributions to the magnitude and distance effects, supporting the holistic model. When numbers were presented simultaneously, unit digits made unique contributions, supporting the compositional model. The SNARC (Spatial-Numerical Association of Response Codes) effect was evident for the whole numbers and the decade digits, but not for the unit digits in both experiments, which indicates that two-digit numbers are represented on one mental number line. Taken together, these results suggested that the representation of two-digit numbers is on a single mental number line, but it depends on the stage of processing whether they are processed holistically or compositionally.     

Serial position effects in implicit memory for multiple-digit numbers

Serial position effects in implicit and explicit memory were investigated in a short-term memory task. A study list composed of four, spatially distributed, two-digit numbers was presented, followed by an item recognition task (explicit test) and an implicit memory task in which participants were asked to verify a simple addition equation where the presented answer was either primed or not primed by one of the number pairs in the study list. Similar serial position effects were observed in explicit and implicit memory, with faster response times for correct decisions on the first than on the later list positions. The presence of a primacy effect but no recency effect is consistent with previous studies of explicit memory with visual presentation. The results suggest that similar principles of temporal information processing govern priming and episodic short-term memory.     

Rhyming and the right hemisphere

Subjects determined whether two successively presented and orthographically different words rhymed with each other. The first word was presented at fixation and the second was presented either to the left or to the right of fixation, either alone (unilateral presentation) or accompanied by a distractor word in the other visual hemifield (bilateral presentation). Subjects were more accurate when the words did not rhyme, when presentation was unilateral, and when the target was flashed to the right visual hemifield. It was predicted that bilateral presentation would produce interference when information from both visual fields was processed by one hemisphere (callosal relay), but not when each of the two hemispheres performed a task independently (direct access). That is, callosal relay tasks should show greater laterality effects with bilateral presentations, whereas direct access tasks should show similar laterality effects with both bilateral and unilateral presentations. Greater laterality effects were observed for bilaterally presented rhyming words, but nonrhyming words showed similar laterality effects for both bilateral and unilateral presentations. These results suggest that judgment of nonrhyming words can be performed by either hemisphere, but that judgment of rhyming words requires callosal relay to the left hemisphere. The absence of a visual field difference with nonrhyming word pairs suggests further that judgment of nonrhyming word pairs may be accomplished by the right hemisphere when presentation is to the left visual field.     

The syllable-length effect in number processing is task-dependent.

Two experiments were run in order to investigate the relationship between syllable length of number names and eye-fixation durations during silent reading of one- and two-digit numbers. In Experiment 1, subjects had to read a series of three numbers and recall them orally; in Experiment 2, subjects had to indicate manually whether the value of the middle number was between the values of the outer numbers. The effect of syllable length was controlled for possible confounding effects of number frequency and number magnitude. Findings indicated that fixation duration depended on syllable length of number names in the first task, but not in the second task. The results call into question the claim that phonological encoding is imperative in visual processing; phonological encoding was used only when the numbers had to be recalled, and not when they were coded for computational purposes.     

The syllable-length effect in number processing is task-dependent

Two experiments were run in order to investigate the relationship between syllable length of number names and eye-fixation durations during silent reading of one- and two-digit numbers. In Experiment 1, subjects had to read a series of three numbers and recall them orally; in Experiment 2, subjects had to indicate manually whether the value of the middle number was between the values of the outer numbers. The effect of syllable length was controlled for possible confounding effects of number frequency and number magnitude. Findings indicated that fixation duration depended on syllable length of number names in the first task, but not in the second task. The results call into question the claim that phonological encoding is imperative in visual processing; phonological encoding was used only when the numbers had to be recalled, and not when they were coded for computational purposes.     

Visuo-spatial processing in working memory

This paper reports four experiments designed to develop a simple technique for the study of visuo-spatial processing within the working memory framework (Baddeley and Hitch, 1974). Experiment 1 involved the matching of successively presented random matrix patterns, as a secondary visual suppression task. This was coupled with rote rehearsal or a visual imagery mnemonic for learning lists of concrete words presented auditorily. Although memory performance with matching dropped overall, the visual mnemonic was differentially affected. Experiment 2 removed the matching decision, with visual presentation of unattended patterns. There was no overall effect of the unattended material, but use of the visual mnemonic was significantly affected. Experiment 3 replicated this result with simpler plain coloured squares as the unattended material.

In Experiment 4, for one group, the unattended material consisted of line drawings of common objects. For a second group, the lists of words for recall were presented visually, with or without unattended speech. The results suggested that unattended pictures disrupt use of a visual mnemonic, while unattended speech disrupts rote rehearsal.

These results suggest that unattended visual material has privileged access to the mechanism(s) involved in short-term visuo-spatial processing and storage. They also suggest that use of a concurrent visual matching task or of unattended visual material may provide tractable techniques for investigating this aspect of cognitive function within the context of working memory.     

The role of preparation and cue-modality in crossmodal task switching

The present study examined the effects of cue-based preparation and cue-target modality mapping in crossmodal task switching. In two experiments, we randomly presented lateralized visual and auditory stimuli simultaneously. Subjects were asked to make a left/right judgment for a stimulus in only one of the modalities. Prior to each trial, the relevant stimulus modality was indicated by a visual or auditory cue. The cueing interval was manipulated to examine preparation. In Experiment 1, we used a corresponding mapping of cue-modality and stimulus modality, whereas in Experiment 2 the mapping of cue and stimulus modalities was reversed. We found reduced modality-switch costs with a long cueing interval, showing that attention shifts to stimulus modalities can be prepared, irrespective of cue-target modality mapping. We conclude that perceptual processing in crossmodal switching can be biased in a preparatory way towards task-relevant stimulus modalities.     

Visual and phonological components of working memory in children

Previous studies have shown that young children's immediate memory for a short series of drawings of objects is mediated by a visual component of working memory, whereas older children rely chiefly upon a phonological component. Three experiments investigated the hypothesis that older children rely also, but to a lesser extent, on visual working memory. Experiment 1 confirmed previous evidence that 11-year-olds' memory is disrupted by phonemic similarity of object names, but is unaffected by visual similarity of the objects themselves. However, when articulatory suppression was used to prevent phonological coding, levels of recall were sensitive to visual rather than phonemic similarity. Experiment 2 compared the effects of interpolating an auditory-verbal or a visual postlist task on memory for drawings viewed either with or without suppression. The visual task had a clear disruptive effect only in the suppression condition, where it interfered selectively with recall of the most recent item. Experiment 3 compared the effects of interpolating an auditory-verbal or a mixed-modality (visual-auditory) postlist task when subjects were not required to suppress. There was greater interference from the mixed-modality task, and this effect was confined to the last item presented. These experiments are taken as confirming the presence of a small but reliable contribution from visual memory in 11-year-old children's recall. As in younger children, visual working memory in 11-year-olds is sensitive to visual similarity and is responsible for a final-item visual recency effect. The results also show that older children's use of visual working memory is usually masked by the more pervasive phonological component of recall. Some implications for the structure of working memory and its development are discussed.     

注意控制与短时记忆的知觉组织

、考察了短时记忆中的知觉组织是否受双作业时指导语引导的注意策略控制。各有24名北京大学本科生参加了自由回忆和顺序回亿实验。实验任务有2种：记忆和声音监控。声音监控或者安排在记忆编码阶段,或者安排在记忆提取阶段。双作业时的指导语类型有3种,分别强调记忆、声音监控或两种作业同样重要。记忆项目表分2种：不分组和知觉分组。研究发现：自由回忆中的知觉组织仅受编码阶段的指导语影响;顺序回忆中的知觉组织仅受提取阶段的指导语影响。作者设想,短时记忆中的知觉组织在编码和提取阶段都受注意控制,但记忆类型不同,注意控制的作用地点和表现形式也有所不同。     

Visual similarity effects on short-term memory for order: The case of verbally labeled pictorial stimuli

Four experiments examined the effect of visual similarity on immediate memory for order. Experiments 1 and 2 used easily nameable line drawings. Following a sequential presentation in either silent or suppression conditions, participants were presented with the drawings in a new, random order and were required to remember their original serial position. In Experiment 3, participants first learned to associate a verbal label with an abstract matrix pattern. Then they completed an immediate memory task in which they had to name the matrices aloud during presentation. At recall, the task required remembering either the order of the matrices or the order of their names. In Experiment 4, participants learned to associate nonword labels with schematic line drawings of faces; the phonemic similarity of the verbal labels was also manipulated. All four experiments indicate that the representations supporting performance comprise both verbal and visual features. The results are consistent with a multiattribute encoding view.     

The storage of physical and name properties in short-term visual memory

Two experiments investigated the hypothesis that short-term visual memory is based primarily on physical features of the visual input. Subjects were required to recall visually presented figures or the names of those figures presented either visually or aurally at a number of different retention intervals. Subjects shadowed words during the retention interval presented aurally in Experiment I and visually in Experiment II. In both experiments, figures were recalled better than names and no differences in recall of names were found due to presentation modality. Recall of both names conditions showed a steady decline across retention intervals whereas recall of figures remained at a relatively high level. These findings were interpreted as providing further support for the existence of short-term visual memory not subject to auditory recoding and based primarily on physical features of the input. It was suggested that such visual memory is limited in capacity so that input exceeding this capacity is recoded into an auditory-verbal-linguistic form.     

The organisation of musical semantic memory: Evidence from false memories for familiar songs

By adapting a well-known paradigm for studying memory for words—the Deese-Roediger-McDermott or DRM paradigm (Deese, 1959, Roediger & McDermott, 1995)—the two experiments reported here explore memory for song titles and song clips. Participants were presented with five song titles (Experiment 1a) or five 30-second song clips (Experiment 1b) for each of nine popular artists (e.g., Robbie Williams). The most popular song identified for each artist in a pilot task was omitted from the sets of titles/clips. Following a distractor task, participants were asked to write down as many of the songs as they could recall. They were also asked to return a week later and complete a second recall task. Participants falsely recalled a significant number of the related but non-presented songs in both experiments and this increased a week later, while correct recall for presented items decreased. The results are discussed in terms of theory for musical memory as well as in the context of providing a novel method for exploring the organisation of musical memory.     

Shifting attention between the ears

Subjects were asked to recall lists of digits presented either alternately to right and left ears or successively to both. Performance was worse with alternating than with successive lists and the decrement was greater with the faster presentation rate. However, there was no interaction between type of presentation and either digit length or list length. The latter finding suggests that the effect arises in perception rather than in memory and is consistent with the idea that it takes time to shift attention or reset the parameters for perceptual processing of alternating monaural speech items.     

Evidence of amodal representation of small numbers across visuo-tactile modalities in 5-month-old infants

Two experiments investigated 5-month-old infants’ amodal sensitivity to numerical correspondences between sets of objects presented in the tactile and visual modes. A classical cross-modal transfer task from touch to vision was adopted. Infants were first tactually familiarized with two or three different objects presented one by one in their right hand. Then, they were presented with visual displays containing two or three objects. Visual displays were presented successively (Experiment 1) or simultaneously (Experiment 2). In both experiments, results showed that infants looked longer at the visual display which contained a different number of objects from the tactile familiarization phase. Taken together, the results revealed that infants can detect numerical correspondences between a sequence of tactile and visual stimulation, and they strengthen the hypothesis of amodal and abstract representation of small numbers of objects (two or three) across sensory modalities in 5-month-old infants.     

Memory scanning of described images and undescribed images: Hemispheric differences

Seamon (1972) has found that reaction times (RTs) to memory probes do not increase with memory set size (M) for words encoded in mental images in a memory scanning task. Rothstein and Atkinson (1975) have failed to replicate Seamon’s results. Experiment 1 investigated this discrepancy by manipulating one methodological difference (whether images were or were not described) between the two investigations. Results revealed that described images produced typical linear increases in RT with M. Undescribed images, however, revealed no change in RT with M for positive probes (i.e., the word presented was contained in the current memory set). Experiment 2 manipulated to which visual field probes were presented (RVF — right visual field; LVF = left visual field). Results showed that the imagery group showed no relation between RT and M for probes presented to the LVF, but a linear relation for probes presentedto the RVF. Described-image and repetition groups revealed a linear relation between RT and M no matter which visual field received the probe.     

Recall of letters from the left and right visual half-fields under unilater and bilateral presentation.

Bilateral presentation in the visual half-field greatly increases superiority of the right visual half-field in tachistoscopic recognition of words when fixation is controlled using a center digit. Two experiments explored left-right asymmetry with bilateral presentation on a visual half-field short-term memory task, with fixation controlled by a sequence of letters at fixation. A total of 40 subjects served in the two experiments, which compared recall under unilateral versus bilateral presentation to the visual half-field. Bilateral presentation increased over-all recall from the last serial position but did not alter asymmetry of the visual half-field. As in previous experiments, the superiority of the right visual half-field was greatest from the initial serial positions. It was concluded that asymmetry of the visual half-field on this recall task with controlled fixation depends primarily on masking and short-term memory but is independent of unilateral-bilateral presentation.     

Memory while shadowing

Subjects were asked to repeat verbally (shadow) English words which were presented to one ear. They were then tested for their memory of two-digit numbers which were presented to their other ear. It is demonstrated that subjects have no memory for these digits if they must continue to shadow for 20 sec. before being tested on their memory for the digits. However, if tested immediately after the digit presentation, they do remember some digits. Hence, verbal material presented on non-attended channels gets into a short-term memory, but is not transferred into long-term memory.