What limits working memory capacity? Evidence for modality-specific sources to the simultaneous storage of visual and auditory arrays

There is considerable debate on whether working memory (WM) storage is mediated by distinct subsystems for auditory and visual stimuli (Baddeley, 1986) or whether it is constrained by a single, central capacity-limited system (Cowan, 2006). Recent studies have addressed this issue by measuring the dual-task cost during the concurrent storage of auditory and visual arrays (e.g., Cocchini, Logie, Della Sala, MacPherson, & Baddeley, 2002; Fougnie & Marois, 2006; Saults & Cowan, 2007). However, studies have yielded widely different dual-task costs, which have been taken to support both modality-specific and central capacity-limit accounts of WM storage. Here, we demonstrate that the controversies regarding such costs mostly stem from how these costs are measured. Measures that compare combined dual-task capacity with the higher single-task capacity support a single, central WM store when there is a large disparity between the single-task capacities (Experiment 1) but not when the single-task capacities are well equated (Experiment 2). In contrast, measures of the dual-task cost that normalize for differences in single-task capacity reveal evidence for modality-specific stores, regardless of single-task performance. Moreover, these normalized measures indicate that dual-task cost is much smaller if the tasks do not involve maintaining bound feature representations in WM (Experiment 3). Taken together, these experiments not only resolve a discrepancy in the field and clarify how to assess the dual-task cost but also indicate that WM capacity can be constrained both by modality-specific and modality-independent sources of information processing.     

In Search of the Unknown: Introduction to the Special Issue

The problem of aesthetic perception occupied Vygotsky throughout his life. Working in different research collectives or networks he worked out different answers but never reached a final solution. Inadequate and incomplete access to his writings unfortunately hinders us from understanding Vygotsky’s ideas and his personal motives. Publication of his notebooks and unadulterated versions of his writings plus an analysis of his research networks will deepen our understanding.     

Representationalism and the perspectival character of perceptual experience

Perceptual experiences inform us about objective properties of things in our environment. But they also have perspectival character in the sense that they differ phenomenally when objects are viewed from different points of view. Contemporary representationalists hold, at a minimum, that phenomenal character supervenes on representational content. Thus, in order to account for perspectival character, they need to indentify a type of representational content that changes in appropriate ways with the perceiver’s point of view. Many representationlists, including Shoemaker and Lycan, argue that such contents are best construed in terms of mind-dependent properties. Other representationalists, including Tye and Dretske, hold that these contents involve only mind-independent properties. Susanna Schellenberg has recently developed an account of perceptual experience that would serve these latter representationalists extremely well. She suggests that we can do justice to the perspectival character of perceptual experience by appeal to representations of a certain type of relational properties, so-called ‘situation-dependent properties.’ In this paper, I critically engage with Schellenberg’s proposal in order to show how mind-independent representationalists can explain perspectival character. I argue that appeal to situation-dependent properties is problematic. I then show that mind-independent representationalists can account for perspectical character by means of scenario contents in Christopher Peacocke’s sense.     

The effect of study time distribution on learning and retention: a Goldilocks principle for presentation rate

In 2 experiments, we investigated the effect of presentation rate on both immediate (5 min) and delayed (2 days) cued recall of paired associates. Word pairs were presented for a total of 16 s per pair, with presentation duration of individual presentations varying from 1 to 16 s. In Experiment 1, participants studied word pairs with presentation rates of 16 × 1 s, 8 × 2 s, 4 × 4 s, 2 × 8 s, or 1 × 16 s. A nonmonotonic relationship was found between presentation rate and cued recall performance. Both short (e.g., 1 s) and long (e.g., 16 s) presentation durations resulted in poor immediate and delayed recall, compared with intermediate presentation durations. In Experiment 2, we replicated these general findings. Moreover, we showed that the 4 s condition resulted in less proportional forgetting than the 1 s and the 16 s conditions.     

Decomposing the interaction between retention interval and study/test practice: the role of retrievability

Even without feedback, test practice enhances delayed performance compared to study practice, but the size of the effect is variable across studies. We investigated the benefit of testing, separating initially retrievable items from initially nonretrievable items. In two experiments, an initial test determined item retrievability. Retrievable or nonretrievable items were subsequently presented for repeated study or test practice. Collapsing across items, in Experiment 1, we obtained the typical cross-over interaction between retention interval and practice type. For retrievable items, however, the cross-over interaction was quantitatively different, with a small study benefit for an immediate test and a larger testing benefit after a delay. For nonretrievable items, there was a large study benefit for an immediate test, but one week later there was no difference between the study and test practice conditions. In Experiment 2, initially nonretrievable items were given additional study followed by either an immediate test or even more additional study, and one week later performance did not differ between the two conditions. These results indicate that the effect size of study/test practice is due to the relative contribution of retrievable and nonretrievable items.     

自闭症儿童的中心信息整合及其与心理理论的关系

研究用积木测验和镶嵌图形测验测量中心信息整合,用5个信念任务测量心理理论能力,比较了12名自闭症儿童和同等言语能力的28名正常儿童的表现,并分析了心理理论和中心信息整合的相关。结果表明:(1)中心信息整合的测量指标积木测验和镶嵌图形测验成绩保持中高度相关;(2)自闭症儿童中心信息整合显著弱于正常儿童;(3)心理理论和中心信息整合成绩相互独立。     

繁殖笼内川金丝猴社群结构的研究

记录了繁殖笼内川金猴(Rhinopithecus roxellanae)成员之间发生的攻击和屈服行为的指向和次数,采用计算优势指数的方法,对数据进行统计和分析。通过优势指数的排列,以及与之有关事件的分析,结果表明繁殖笼内川金丝猴成员之间存在优势等级关系,但不是简单的线性排列;成员之间存在着有弹性的,有回旋余地的,复杂的社会网。     

恒河猴在繁殖笼内的等级结构

有关非人灵长类社群结构的问题,国外已多有研究。许多学者认为无论在野外,或是在捕后(笼养)条件下进行观察都发现只要有几只动物在一起,形成一个群,那末群内的个体之间必然形成等级关系,而这种等级关系是线性排列的。换句话说,如果一群有A、B、C、D、E五只动物的话,它们的等级关系就是这样排列的:A>B>C>D>E。     

Experimental validation of two MIQ scales

Two Minnesota Importance Questionnaire (MIQ) scales, Creativity and Independence were validated by experiment. Subjects were exposed to four task conditions representing joint combinations of high or low levels of Creativity and Independence. As a behavioral criterion of preference, subjects were then required to work for 12 sessions, each session under any (of the four) task condition of their choice. The behavioral results were consistent with the subjects' MIQ score levels on the two scales, thereby validating the scales.