The importance of the keyword-generation method in keyword mnemonics

Keyword mnemonics is under certain conditions an effective approach for learning foreign-language vocabulary. It appears to be effective for words with high image vividness but not for words with low image vividness. In this study, two experiments were performed to assess the efficacy of a new keyword-generation procedure (peer generation). In Experiment 1, a sample of 363 high-school students was randomly into four groups. The subjects were required to learn L1 equivalents of a list of 16 Latin words (8 with high image vividness, 8 with low image vividness), using a) the rote method, or the keyword method with b) keywords and images generated and supplied by the experimenter, c) keywords and images generated by themselves, or d) keywords and images previously generated by peers (i.e., subjects with similar sociodemographic characteristics). Recall was tested immediately and one week later. For high-vivideness words, recall was significantly better in the keyword groups than the rote method group. For low-vividness words, learning method had no significant effect. Experiment 2 was basically identical, except that the word lists comprised 32 words (16 high-vividness, 16 low-vividness). In this experiment, the peer-generated-keyword group showed significantly better recall of high-vividness words than the rote method groups and the subject generated keyword group; again, however, learning method had no significant effect on recall of low-vividness words.     

长期高策略性技能训练对运动员大脑白质结构的影响：一项DTI研究

目前关于运动员经验优势的脑机制还存在争议, 尤其对于涉及较多认知过程参与的高策略性技能项目运动员, 其大脑白质结构可塑性变化还需进一步探究。研究横向对比了乒乓球运动员和非运动员大脑白质纤维束的弥散张量成像数据。结果发现, 相比于非运动员, 乒乓球运动员在连接背侧和腹侧通路脑区的双侧皮质脊髓束、左侧上纵束、左侧下纵束和双侧额枕下束的各向异性值(FA)更大, 进一步分析发现, 部分腹侧通路白质纤维束FA增加的原因是径向扩散系数(RD)下降。研究结果支持了动作双通路模型。提示经过长期高策略性技能训练, 乒乓球运动员在背侧和腹侧通路上的白质纤维束结构完整性增强。     

Interactions of reading and semantics along the ventral visual processing stream

Converging evidence supports a distributed-plus-hub view of semantic processing, in which there are distributed modular semantic sub-systems (e.g., for shape, colour, and action) connected to an amodal semantic hub. Furthermore, object semantic processing of colour and shape, and lexical reading and identification, are processed mainly along the ventral stream, while action semantic processing occurs mainly along the dorsal stream. In Experiment 1, participants read a prime word that required imagining either the object or action referent, and then named a lexical word target. In Experiments 2 and 3, participants performed a lexical decision task (LDT) with the same targets as in Experiment 1, in the presence of foils that were legal nonwords (NW; Experiment 2) or pseudohomophones (PH; Experiment 3). Semantic priming was similar in effect size regardless of prime type for naming, but was greater for object primes than action primes for the LDT with PH foils, suggesting a shared-stream advantage when the task demands focus on orthographic lexical processing. These experiments extend the distributed-plus-hub model, and provide a novel paradigm for further research.     

Mental image generation and the contrast sensitivity function

In one experiment, observers were instructed to generate small and large visual mental images in a light-adapted or a dark-adapted viewing condition, and to rate the vividness of each image. In light-adapted viewing, small images were generated faster than large images. However, the pattern of results was reversed in dark-adapted viewing. Furthermore, the dark-adapted images were more vivid than the light-adapted images. The results show that mental images can be mapped onto some regions of the contrast sensitivity function (CSF), so that the latency (and vividness) of a particular image can be predicted. Since the CSF reflects visual processes occurring mainly in V1, the results agree with functional magnetic resonance imaging data in indicating that early visual pathways participate in imagery. Nonetheless, imagery and perception may involve different processes hosted by the same neural structures as indicated by the direct relationship between image latency and contrast sensitivity.     

A bottleneck in face identification: repetition priming from flanker images

There is evidence that face processing is capacity-limited in distractor interference tasks and in tasks requiring overt recognition memory. We examined whether capacity limits for faces can be observed with a more sensitive measure of visual processing, by measuring repetition priming of flanker faces that were presented alongside a face or a nonface target. In Experiment 1, we found identity priming for face flankers, by measuring repetition priming across a change in image, during task-relevant nonface processing, but not during the processing of a concurrently-presented face target. Experiment 2 showed perceptual priming of the flanker faces, across identical images at prime and test, when they were presented alongside a face target. In a third Experiment, all of these effects were replicated by measuring identity priming and perceptual priming within the same task. Overall, these results imply that face processing is capacity limited, such that only a single face can be identified at one time. Merely attending to a target face appears sufficient to trigger these capacity limits, thereby extinguishing identification of a second face in the display, although our results demonstrate that the additional face remains at least subject to superficial image processing.     

Implicit memory in spelling from word images

Summary A series of experiments is reported concerning implicit memory in imaginal processing. In the standard condition, subjects had to encode word images before spelling a word. The spelling task was repeated in the test phase with the same words and with additional control words. Spelling times were registered after the image encoding. Implicit memory has been detected if repeated words can be spelled faster than control words. Experiment 1 showed that levels of processing manipulations (such as the additional generation of meaning images at encoding or variations in word concreteness) favor explicit memory, but do not show up in implicit memory. Experiment 2 demonstrated that implicit memory disappears if spelling at encoding took place on visually present words. Experiment 3 investigated whether the focusing of specific letter positions within the image may contribute to the effect, but this was not found. According to a processing view that underlies our task analysis, implicit memory depends on transfer-appropriate processing and is attributed to processes of image encoding or generation and image reconstruction or regeneration.     

Eye movement control during scene viewing: Immediate degradation and enhancement effects of spatial frequency filtering

What controls how long the eyes remain fixated during scene perception? We investigated whether fixation durations are under the immediate control of the quality of the current scene image. Subjects freely viewed photographs of scenes in preparation for a later memory test while their eye movements were recorded. Using the saccade-contingent display change method, scenes were degraded (Experiment 1) or enhanced (Experiment 2) via blurring (low-pass filtering) during predefined saccades. Results showed that fixation durations immediately after a display change were influenced by the degree of blur, with a monotonic relationship between degree of blur and fixation duration. The results also demonstrated that fixation durations can be both increased and decreased by changes in the degree of blur. The results suggest that fixation durations in scene viewing are influenced by the ease of processing of the image currently in view. The results are consistent with models of saccade generation in scenes in which moment-to-moment difficulty in visual and cognitive processing modulates fixation durations.     

执行控制资源损耗对自传体记忆生动性和情绪的影响

旨在探究健康个体执行控制资源损耗对自传体记忆生动性及情绪的影响。实验一采用Stroop任务探讨了一般执行控制资源损耗的影响,结果发现损耗组自传体记忆生动性和情绪强度显著低于控制组。实验二进一步探讨不同的执行控制资源损耗的影响,结果显示中央执行的资源损耗对生动性和情绪强度影响最大,而视空间模板与语音环之间没有显著差异。实验结果支持了自传体记忆的执行控制资源受损理论和资源有限理论,并对临床治疗具有实际应用价值。     

Testing the dorsal stream attention hypothesis: Electrophysiological correlates and the effects of ventral stream damage

The roles of dorsal and ventral processing streams in visual orienting and conscious perception were examined in two experiments. The first employed high density EEG with source localization. The second comprised a neuropsychological case study. Visual orienting was assessed with an attention procedure, where peripheral letters cued participants towards a target location. In the perception procedure participants responded to the same letters by performing an explicit conscious discrimination. In Experiment 1, the peripheral letters elicited rapid dorsal stream activation in the attention procedure, and this activation preceded top-down enhancement of target processing in occipital cortex. In the perception procedure early ventral stream activation was seen. In addition, peripheral letters elicited an “early directing attention negativity” (EDAN) over parietal recording sites in the attention procedure, but not in the perception procedure. In Experiment 2, a patient with a bilateral ventral stream lesion but preserved dorsal stream function showed clear disruption to performance in the perception procedure, whilst exhibiting a normal visual orienting effect in the attention procedure. Taken together these findings (1) highlight the distinct roles of the dorsal and ventral streams in attention and perception, and (2) suggest how these streams might interact, via reentrant effects of attention on perceptual processing.     

Varieties of size-specific visual selection

Compared time to evaluate stimuli of varying sizes. When Ss expect an upcoming stimulus to be a certain size, response time increases with the disparity between expected and actual size. There are, however, 2 size adjustment processes, and they reflect 2 types of visual selection. In the first, a shape-specific image representation is used to separate a visual object from a superimposed distractor. These representations require the type of slow size scaling demonstrated in imagery experiments. The second size scaling process is faster and not shape-specific. At any given time the visual system is set to process information at a particular scale, and that scale can be adjusted to match an object's size. Because both selection mechanisms depend on size, they probably occur at a relatively low, spatially organized processing level. These findings lead to a new explanation for results that had been taken as evidence for attentional selection at the level of object representations.     

Effects of eye movements on the rate of discovery and the vividness of visual images

Two studies investigated the effects of eye movements on the rate of discovery and the vividness of visual images. Eye movements were manipulated by having three conditions: (1) The Ss were instructed to make eye movements while generating images to noun pairs; (2) the Ss were instructed not to make eye movements, but to think about making eye movements while generating images to noun pairs; (3) the Ss were instructed not to make eye movements and not to think about making eye movements while generating images to noun pairs. In addition, the ease of generating images was manipulated by using noun pairs that differed in their image-evoking capacity; five of the noun pairs consisted of high imagery-evoking nouns and five consisted of low imagery-evoking nouns. The two experiments were similar, with the exception that a between-groups design was used in Experiment 1, whereas Experiment 2 employed a within-Ss design. The results of both experiments showed highly significant effects of noun-pair type on both the rate of discovery and the vividness of images, with the fastest and most vivid images occuring to the high-imagery noun pairs. The effects of the eye-movement conditions on the rate of discovery and the vividness of the images were not significant in either experiment, and these findings are discussed in terms of the relationship of ocular activity to imagery.     

Interactions between the dorsal and the ventral pathways in mental rotation: An fMRI study

In this fMRI study, we examined the relationship between activations in the inferotemporal region (ventral pathway) and the parietal region (dorsal pathway), as well as in the prefrontal cortex (associated with working memory), in a modified mental rotation task. We manipulated figural complexity (simple vs. complex) to affect the figure recognition process (associated with the ventral pathway) and the amount of rotation (0° vs. 90°), typically associated with the dorsal pathway. The pattern of activation not only showed that both streams are affected by both manipulations, but also showed an overadditive interaction. The effect of figural complexity was greater for 90° rotation than for 0° in multiple regions, including the ventral, dorsal, and prefrontal regions. In addition, functional connectivity analyses on the correlations across the time courses of activation between regions of interest showed increased synchronization among multiple brain areas as task demand increased. The results indicate that both the dorsal and the ventral pathways show interactive effects of object and spatial processing, and they suggest that multiple regions interact to perform mental rotation.     

A right visual field advantage for visual processing of manipulable objects

Information about object-associated manipulations is lateralized to left parietal regions, while information about the visual form of tools is represented bilaterally in ventral occipito-temporal cortex. It is unknown how lateralization of motor-relevant information in left-hemisphere dorsal stream regions may affect the visual processing of manipulable objects. We used a lateralized masked priming paradigm to test for a right visual field (RVF) advantage in tool processing. Target stimuli were tools and animals, and briefly presented primes were identical to or scrambled versions of the targets. In Experiment 1, primes were presented either to the left or to the right of the centrally presented target, while in Experiment 2, primes were presented in one of eight locations arranged radially around the target. In both experiments, there was a RVF advantage in priming effects for tool but not for animal targets. Control experiments showed that participants were at chance for matching the identity of the lateralized primes in a picture?Cword matching experiment and also ruled out a general RVF speed-of-processing advantage for tool images. These results indicate that the overrepresentation of tool knowledge in the left hemisphere affects visual object recognition and suggests that interactions between the dorsal and ventral streams occurs during object categorization.     

Measuring the size of mental images

Mental images seem to have a size; the experimental problem was to map that image size onto a scale of physical measurement. To this end, two experiments were conducted to measure the size of mental images in degrees of visual angle. In Experiment 1, college students employed light pointers to indicate the horizontal extent of projected mental images of words (the letter string, not the referent). Imagined words covered about 1.0 degress of visual angle per letter. In Experiment 2, a more objective eye-movement response was used to measure the visual angle size of imagined letter strings. Visual angle of eye movement was found to increase regularly as the letter distance between the fixation point and a probed letter position increased. Each letter occupied about 2.5 degrees of visual angle for the four-letter strings in the control/default size condition. Possible relations between eye movements and images are discussed.     

Detecting conjunctions of color and form in parallel

Certain theories of visual attention assume that at least one processing stage must be serial when the target of search is defined as the conjunction of two or more separable features. To explain why conjunction-search response times do not always form linearly increasing functions of display size, recent versions of this general model have posited the existence of an early parallel process that guides the serial stage toward display elements that are likely targets. Other models have relaxed the seriality assumption, allowing for a limited number of parallel decisions. In the three experiments reported here, a redundant-target detection task was used with conjunctively defined targets and display sizes of two (Experiment 1), one or two (Experiment 2), and six (Experiment 3). In all three experiments, strong evidence for parallel processing was observed. The implications for models of elementary visual processes are discussed.     

Dorsal and ventral processing under dual-task conditions

It is widely acknowledged that visual input is processed along two anatomically and functionally distinct pathways--a ventral pathway for conscious perception and a dorsal pathway for action control. The present study investigated whether the apparent direct and unmediated processing in the dorsal stream is subject to capacity limitations. Specifically, we tested whether a simple dorsal task of grasping an object is affected by the psychological refractory period (PRP), a well-known indication of capacity limitations. Subjects performed an auditory choice reaction task and then, following varying delays, had to judge an object's width (ventral task) or grasp an object across its width (dorsal task). Although these tasks were differentially affected by irrelevant variation of the objects' length, they were subject to comparable dual-task interference. These results show that despite important differences between ventral and dorsal information processing, both modes of processing are constrained by limited capacities.     

Size scaling and its effect on letter detection

Two ways of scaling letter size across eccentricity were investigated in a choice reaction time (CRT) task. Experiments 1 and 2 tested cortical magnification theory (M-scaling), while Experiment 3 used scaled sizes drawn from Anstis’s regression formula (A-scaling). Experiment 4 compared both scaling techniques, together with the effect of exposure duration and the absolute size of the foveal letter. Results showed that scaling effectiveness improved when large rather than small foveal letters were used. A-scaling with a large foveal letter provided a good fit for the data at parafoveal locations, but underestimated the letter sizes needed at large eccentricities. M-scaling with a large foveal letter size produced CRTs that were independent of eccentricity. Exposure duration did not substantially affect performance.     

Reducing the vividness and emotional impact of distressing autobiographical memories: the importance of modality-specific interference

Experimental analogues of post-traumatic stress disorder suggest that loading the visuospatial sketchpad of working memory with a concurrent task reduces the vividness and associated distress of predominantly visual images. The present experiments explicitly tested the hypothesis that interfering with the phonological loop could analogously reduce the vividness and emotional impact of auditory images. In Experiment 1, 30 undergraduates formed non-specific images of emotive autobiographical memories while performing a concurrent task designed to load either the visuospatial sketchpad (eye movements) or phonological loop (articulatory suppression). Participants reported their images to be primarily visual, corresponding to the greater dual-task disruption observed for eye movements. Experiment 2 instructed participants to form specifically visual or auditory images. As predicted, concurrent articulation reduced vividness and emotional intensity ratings of auditory images to a greater extent than did eye movements, whereas concurrent eye movements reduced ratings of visual images much more than did articulatory suppression. Such modality-specific dual-task interference could usefully contribute to the treatment and management of intrusive distressing images in both clinical and non-clinical settings.     

fMRI evidence for dorsal stream processing abnormality in adults born preterm

We investigated the consequences of premature birth on the functional neuroanatomy of the dorsal stream of visual processing. fMRI was recorded while sixteen healthy participants, 8 (two men) adults (19 years 6 months old, SD 10 months) born premature (mean gestational age 30 weeks), referred to as Premas, and 8 (two men) matched controls (20 years 1 month old, SD 13 months), performed a 1-back memory task of Object or Grip information using a hand grasping a drinking vessel as stimulus. While history of prematurity did not significantly affect task performance, Group by Task analysis of variance in regions of interest spanning the occipital, temporal and parietal lobes revealed main effects of Task and interactions between the two factors. Object processing activated the left inferior occipital cortex and bilateral ventral temporal regions, belonging to the ventral stream, with no effect of Group. Grip processing across groups activated the early visual cortex and the left supramarginal gyrus belonging to the dorsal stream. Group effect on the brain activity during Grip suggested that Controls represented the actions’ goal while Premas relied more on low-level visual information. This shift from higher- to lower-order visual processing between Controls and Premas may reflect a more general trend, in which Premas inadequately recruit higher-order visual functions for dorsal stream task performance, and rely more on lower-level functions.