内隐重复效应影响外显工作记忆的年龄差异

采用延迟样本匹配任务并控制被试对部分项目的有意识学习经验, 当前研究考察了老年被试与青年被试在追逐靶、排除分心物的过程中, 重复启动效应如何受到项目外显学习经验的影响。老年被试和青年被试首先学习一些物体图片, 这些熟悉的图片与一些新图片作为之后工作记忆任务的靶或分心物。结果发现, 老年被试与青年被试在追逐靶和排除分心物的过程中均受到项目之前学习经验的影响。无论是老年被试还是青年被试, 对靶的反应时均快于对分心物的反应时, 对外显学习过的靶(即熟悉靶)的反应时快于对未学习过的靶(即新靶)的反应时, 而拒绝熟悉的分心物需要的时间长于拒绝新分心物的时间。其次, 老年被试与青年被试均表现出对靶的重复效应, 即当靶(无论是熟悉的还是新的)在任务中重复出现时, 对其的反应时加快; 然而, 对分心物的重复效应显著减小。随着项目多次重复, 重复效应整体上减小, 但该效应的变化受到项目属性(靶或分心物)以及项目之前学习经验的影响。重要的是, 当熟悉的分心物反复出现时, 老年被试不但没有出现重复效应, 反而在拒绝该熟悉分心物上表现出困难, 反应时显著延长, 而在青年被试上没有该表现。这些结果说明, 老年被试的工作记忆任务成绩容易受到内隐熟悉性的干扰, 重复出现的干扰项产生的熟悉性使得老年被试难以拒绝。     

人类面孔识别工作记忆的脑电位特征

采用事件相关电位(ERPs)技术探索延迟匹配任务范式下面孔识别工作记忆的脑电位特征。实验以面孔图片为刺激,在校大学生被试完成靶匹配工作记忆任务。结果发现,被试识别靶面孔及分心物面孔时均在枕颞区两侧诱发N170,且靶与分心物的N170振幅在相同电极上都没有显著差异,在颞区两侧的P7和P8上差异显著;无论靶面孔还是分心物面孔,工作记忆的 ERPs均产生了 P300成分。在分别追踪新靶和熟悉靶的工作记忆任务条件下,靶与分心物的ERPs波形在250 ms后出现分离,且靶刺激波幅均比分心物更正,新靶比熟悉靶更正。熟悉分心物与新分心物之间显示出250~650 ms的前额区旧/新效应,在晚期的450~650 ms时段,新工作记忆比旧工作记忆波幅更正。这些结果表明,面孔识别的N170效应可能反映的是面孔知觉的整体加工,且 N170的右半球优势具体为颞区的右侧优势;先前的面孔学习会影响工作记忆期间大脑对面孔的识别反应。     

归类任务中负启动效应与分心物特性抑制的实验研究

以汉语单字词为材料,采用负启动技术,在归类任务中考察了作为负启动效应根源的扩散抑制是否遵循资源有限机制以及在要求操作反应的情况下是否也能获得来自分心物特性抑制的负启动效应。结果表明：１．被试对曾在启动显示中作为分心物的探测目标的反应时随着启动显示中分心物数目的增加而缩短。因此,扩散抑制遵循资源有限机制;２．在操作反应要求下能获得非常显著的来自分心物特性抑制的负启动效应。     

小学生和成人不同注意条件下的感数与计数加工的比较研究

采用经典的空间线索范式,以成年人和小学二、四、六年级的学生为研究对象,考察了内、外源注意对感数和计数加工过程的影响。结果表明：（1）六年级学生和成人的感数范围为1-3或4,计数范围为4或5以上,二、四年级学生的感数范围在1-3,计数范围在4以上,支持感数和计数分离的观点。（2）对感数加工,成人和六年级学生均不受两种注意条件的影响,而对计数加工,外源性注意条件下的反应比内源性注意快;二年级学生1-6的数量加工受两种注意条件的影响,四年级学生1-5的加工不受两种注意条件的影响。（3）成人和小学生在感数和计数加工上都存在线索效应。以上结果说明：二-四年级是发展的关键期,随着年龄的增加,儿童逐渐有意识地有效利用内源和外源性线索进行数量加工,其注意指向性更明确;从发展的角度为选择注意加工理论提供了发展证据。     

对分心物特性抑制中位置因素的排除

本研究以汉语单字词为材料,使用反应时技术,考察在归类住条中分心物的位置因素是否也与分心物特性因素一样,影响被试对探测显示中目标的反应时间（RTDT）。结果表明,RTDT不随分心物位置数目变化而变化,只随着分心物特性数目变化而变化．由此得出,象归类这种属于语义表征的、与位置无关的任务中被试并不抑制分心物出现的位置,并可进一步推论,分心物抑制可能是一种灵活机制。     

负性情绪干扰行为抑制控制:一项事件相关电位研究

以往研究提示,行为抑制控制与视觉情绪加工的神经活动存在交互作用,而视觉材料诱发的正、负情绪如何影响行为控制加工过程尚不清楚。采用双选择情绪oddball范式与事件相关电位(ERP)技术,本研究假设视觉情绪刺激的呈现对个体的行为控制能力具有显著影响。实验要求被试对标准刺激与偏差刺激(85%vs.15%)分别做不同的按键反应。偏差刺激由正、负、中三种来自中国情绪图片系统的情绪图片组成。行为结果发现,负性条件下的反应时间显著长于中性与正性条件,而三类偏差刺激的反应时均显著长于标准刺激的反应时。ERP结果显示,不论效价,在240～300ms与350～550ms两个时间窗口,偏差刺激与标准刺激诱发的平均波幅差异显著,表明本研究条件下行为抑制控制效应显著。在代表行为控制加工的偏差-标准差异波中,在上述两窗口内分别出现显著的N2与P3成分。负性条件下N2及P3潜伏期显著长于中性条件;而负性条件下N2波幅显著大于而P3波幅显著小于中性条件。相反,正性条件下N2波幅显著小于而P3波幅显著大于中性条件。因此,本研究从行为与脑电两个层面揭示了情绪对行为控制过程的影响:负性情绪减弱个体的行为控制能力,从而导致个体对反应冲突的觉察变慢及对优势反应的抑制过程更长。相反,正性情绪对行为控制过程可能具有促进作用。     

对分心物特性抑制中位置因置的排除

本研究以汉语单字词灰材料,使用反应时技术,考察在归类任务中分心物的位置因素是否也与分心物特性因素一样,影响被试对探测显示中目标的反应时间,结果表明,ＲＴＤＴ不随主物位置数目变化而变化。只随着分心物特性数目变化而变化。由此得出,象归类这种属于语义表征的、与位置无关的任务 并不抑制分心物出现的位置,并可进一步推论,分心物抑制可能是一种灵活机制。     

网络成瘾者工作记忆能力的ERP研究

旨在探究网络成瘾者和非成瘾者在言语工作记忆任务和视觉工作记忆任务中,面对网络相关刺激与网络无关刺激的ERP成分差异。利用词汇和图片材料,招募网络成瘾者以及非成瘾者各30名参加了N-back（N=2）工作记忆任务的ERP实验,同时记录行为数据及EEG,离线处理数据。结果发现：（1）在视觉工作记忆任务中,与网络无关图片相比,两组被试对网络相关图片的反应时显著更长,正确率也显著更低,而在言语工作记忆中无此显著差异;（2）非成瘾者面对网络相关图片产生的N2波幅显著高于网络无关图片,网络成瘾者对网络相关图片产生的P3波幅显著高于网络无关图片。两组差异表明网络成瘾者在言语工作记忆和视觉工作记忆上对网络相关刺激的早期加工存在差异,网络成瘾者对网络相关图片的视觉工作记忆水平较低。     

任务无关情绪刺激对工作记忆信息更新的影响:来自ERP的证据

任务无关的情绪刺激如何对工作记忆的信息更新过程产生影响还不清楚。本研究采用情绪N-back任务,结合事件相关电位技术调查情绪对工作记忆信息更新的影响。ERP结果显示,在0-back任务中,负性分心物诱发的P3显著小于中性分心物,表明其干扰了工作记忆信息更新过程;而在2-back任务中,负性分心物诱发的P3与中性分心物没有显著差异,表明其未对信息更新表现出干扰效应。该结果支持了情绪与认知加工的双竞争模型。     

物体分类任务中线索效应的ERP研究

本实验采用ERP技术,对图片分类任务中的线索效应进行研究。实验任务为:图形形状判断、动物/非动物判断。靶刺激图片前呈现线索。线索分为有效线索、无效线索和中性线索。结果发现:(1)有效线索条件下对靶刺激的早期知觉再认得到易化——知觉加工成分波幅下降;(2)有效线索条件下,靶刺激中与任务相关的信息得到加工——任务相关的特异性成分增强。有效线索易化对靶刺激的知觉辨认,提取与线索提供背景相关的信息,促进行为反应。     

The role of pattern recognition in children's exact enumeration of small numbers

Enumeration can be accomplished by subitizing, counting, estimation, and combinations of these processes. We investigated whether the dissociation between subitizing and counting can be observed in 4‐ to 6‐year‐olds and studied whether the maximum number of elements that can be subitized changes with age. To detect a dissociation between subitizing and counting, it is tested whether task manipulations have different effects in the subitizing than in the counting range. Task manipulations concerned duration of presentation of elements (limited, unlimited) and configuration of elements (random, line, dice). In Study 1, forty‐nine 4‐ and 5‐year‐olds were tested with a computerized enumeration task. Study 2 concerned data from 4‐, 5‐, and 6‐year‐olds, collected with Math Garden, a computer‐adaptive application to practice math. Both task manipulations affected performance in the counting, but not the subitizing range, supporting the conclusion that children use two distinct enumeration processes in the two ranges. In all age groups, the maximum number of elements that could be subitized was three. The strong effect of configuration of elements suggests that subitizing might be based on a general ability of pattern recognition.     

Effects of distraction on visual enumeration in children and adults

Speeded enumeration of visual stimuli typically produces a bilinear function, with a shallow subitizing rate (<100 ms/item) up to 3-4 items (subitizing span) and a steeper counting rate (~300 ms/item) thereafter. FINST theory (L. M. Trick & Z. W. Pylyshyn, 1993, 1994) suggests that subitizing of targets is possible in the presence of distractors if attention is not required for target detection, but this has not been tested in children. The present study explored enumeration without distractors (Os alone) and with distractors (Os among Xs) in 35 children aged 6-11 years and 17 adults. Subitizing span increased significantly from childhood to adulthood, and counting rate increased significantly with age. Bilinear functions were significantly better than linear fits to the data for most children and adults both without distractors (97% and 100%, respectively) and with distractors (89% and 94%), consistent with their efficient visual search for a single O among multiple Xs. These findings are discussed in comparison with those from new modeling of earlier enumeration data from young and older adults, revealing striking asymmetries in subitizing with distractors between development and aging.     

Subitizing and counting in typical and atypical development

Enumeration performance in standard dot counting paradigms was investigated for different age groups with typical and atypically poor development of arithmetic skills. Experiment 1 showed a high correspondence between response times and saccadic frequencies for four age groups with typical development. Age differences were more marked for the counting than the subitizing range. In Experiment 2 we found a discontinuity between subitizing and counting for dyscalculic children; however, their subitizing slopes were steeper than those of typically developing control groups, indicating a dysfunctional subitizing mechanism. Across both experiments a number of factors could be identified that affect enumeration in the subitizing and the counting range differentially. These differential patterns further support the assumption of two qualitatively different enumeration processes.     

Intentional subitizing: exploring the role of automaticity in enumeration

Subitizing is traditionally described as the rapid, preattentive and automatic enumeration of up to four items. Counting, by contrast, describes the enumeration of larger sets of items and requires slower serial shifts of attention. Although recent research has called into question the preattentive nature of subitizing, whether or not numerosities in the subitizing range can be automatically accessed is yet to be empirically tested. In the current study, participants searched for two pre-defined digits in a circular visual-search array. Distractor dots of various set sizes were placed at the centre of the array. Despite the relevance of the distractor numerosities to the target detection task, the distractors did not influence target detection, thereby suggesting that their numerosities were not automatically accessed in Experiment 1. In Experiment 2, participants were explicitly instructed to enumerate the distractor dots. Here, congruent and incongruent distractor numerosities influenced the target detection task, thereby revealing that the distractor dots were capable of generating interference. Experiment 3 ensured that dots were attended by asking participants to detect the luminance of dots. Data confirmed that subitizing was not automatic. The present study also supported the alleged discontinuity between the subitizing and counting ranges because an examination of reaction time gradients in Experiment 2 found the counting gradient to be significantly steeper than the subitizing gradient. In sum, the results suggest that subitizing is a distinct but non-automatic style of enumeration.     

More than superstition: differential effects of featural heterogeneity and change on subitizing and counting

This study investigates the effects of item heterogeneity (differences in color and shape) and moment-to-moment feature change as it relates to the issue of whether subitizing and counting involve different processes. Participants enumerated displays of up to eight items that were either homogeneous or heterogeneous. In situations where the heterogeneous displays always had approximately half of the items of one type and half of the other, heterogeneity significantly sped enumeration in the counting range (6-8 items) and significantly slowed enumeration in the subitizing range (1-3 items), a dissociation that suggests that subitizing and counting involve different operations. Moment-to-moment feature change had no effect on subitizing. However, feature change slowed counting, but only when participants were enumerating heterogeneous items that were half of one type and half of the other, as might be expected if participants were using differences in features to select items by type.     

What dot clusters and bar graphs reveal: subitizing is fast counting and subtraction

In two studies, we found that dot enumeration tasks resulted in shallow-sloped response time (RT) functions for displays of 1-4 dots and steep-sloped functions for displays of 5-8 dots, replicating results implicating subitizing and counting processes for low and high ranges of dots, respectively. Extracting number from a specific type of bar graph within the same numerical range produced a shallow-sloped but scallop-shaped RT function. Factor analysis confirmed two independent subranges for dots, but all bar graph values defined a unitary factor. Significantly, factor scores and asymmetries both showed correlations of bar graph recognition to dot subitizing but not to dot counting, strongly suggesting that subitizing was used in both enumeration of low numbers of dots and bar graph recognition. According to these results, subitizing appears to be a nonverbal process operating flexibly in either additive or subtractive fashion on analog quantities having spatial extent, a conclusion consistent with a fast-counting model of subitizing but not with other models of the subitizing process.     

Effects of age on searching for and enumerating targets that cannot be detected efficiently

We investigated the effects of old age on search, subitizing, and counting of difficult-to-find targets. In Experiment 1, young and older adults enumerated targets (Os) with and without distractors (Qs). Without distractors, the usual subitization-counting function occurred in both groups, with the same subitization span of 3.3 items. Subitization disappeared with distractors; older adults were slowed more overall by their presence but enumeration rates were not slowed by ageing either with or without distractors. In contrast, search rates for a single target (O among Qs) were twice as slow for older as for young adults. Experiment 2 tested and ruled out one account of age-equivalent serial enumeration based on the need to subvocalize numbers as items are enumerated. Alternative explanations based on the specific task differences between detecting and enumerating stimuli are discussed.     

感数——它能告诉我们什么?

研究者在列举任务中发现,被试对3个以内项目的报告既快又准确（一般称之为“感数”）,而对3个以上项目的报告既慢又容易出错误（“计数”）,由此他们提出感数和计数属于两种不同性质的加工过程,一系列行为数据的反应时和正确率指标支持了这一假设。此外,最近的脑成像、电生理研究还发现,感数和计数在对注意的需求上同样存在着分离——感数无需注意,只有计数过程才需注意的参与。在此基础上,研究者从不同角度提出了一些解释感数现象的理论     

Spatial working memory load affects counting but not subitizing in enumeration

The present study investigated whether subitizing reflects capacity limitations associated with two types of working memory tasks. Under a dual-task situation, participants performed an enumeration task in conjunction with either a spatial (Experiment 1) or a nonspatial visual (Experiment 2) working memory task. Experiment 1 showed that spatial working memory load affected the slope of a counting function but did not affect subitizing performance or subitizing range. Experiment 2 showed that nonspatial visual working memory load affected neither enumeration efficiency nor subitizing range. Furthermore, in both spatial and nonspatial memory tasks, neither subitizing efficiency nor subitizing range was affected by amount of imposed memory load. In all the experiments, working memory load failed to influence slope, subitizing range, or overall reaction time. These findings suggest that subitizing is performed without either spatial or nonspatial working memory. A possible mechanism of subitizing with independent capacity of working memory is discussed.