Age-related differences in working memory: ERPs reveal age-related delays in selection- and inhibition-related processes

Faulty inhibition is implicated in age-related working memory decline. ERP signs of selection and inhibition of items in working memory (WM) are, respectively, a cue-locked parietal positivity (～350 ms) and a probe-locked frontal negativity (～520 ms). To determine when in the older age range differences in selective and inhibitory processes might occur, ERPs were recorded in a WM task from 20 young (20–28), 20 young–old (60–70), and 20 old–old (71–82) adults. A 4-digit display was followed by a cue indicating which 2 of 4 digits were relevant. Proactive interference (PI), the reaction time difference between a matching and non-matching to-be-ignored digit was larger, relative to the young, in both older groups. Compared to the young, both the cue- and probe-locked activities were prolonged in the older groups. Although there were no topographic differences among the age groups, the prolonged PI and associated ERPs suggest a relative age-related deficit in inhibition.     

Shared space: Different age groups’ perspectives

BackgroundShared spaces, in the context of road transport, often refer to areas shared by unprotected and protected road users and intended to facilitate a living city space for every-one. A basic idea behind shared spaces is to create traffic safety by inducing some uncertainty. This study investigates how young, middle-aged, and elderly pedestrians experience shared space, as well as whether and, if so, how two shared space designs (without and with large flowerpots) affect this experience.MethodThirty-seven participants, divided into three age groups, participated in the study, conducted in Fisherman’s Square, Västervik, Sweden. An adjacent non-signal-regulated pedestrian crossing was used as a control. Two studies – visual scanning and Q studies – were combined. In the visual scanning study, eye-tracking examined how the two designs affected the participants’ visual scanning behaviour (i.e., what participants looked at) as pedestrians. In the Q-study, Q-methodology was used to examine how the two designs affected the participants’ experiences as pedestrians.ResultsThe visual scanning study showed that different age groups were affected in different ways by designs without and with large flowerpots in the shared space. While the middle-aged participants always glanced more often at traffic-relevant objects, and young participants always glanced equally often at traffic-relevant and non-traffic-relevant objects, the elderly participants changed their visual scanning behaviour depending on the design. Without large flowerpots deployed, the elderly participants glanced more often at traffic-relevant than non-traffic-relevant objects. No such difference was obtained when large flowerpots were deployed. The Q-study showed that participants, regardless of age, experienced no great uncertainty in this shared space. The perceived uncertainty, which nevertheless existed, was reduced with large flowerpots deployed to recreate the traditional division with clear zones where pedestrians could stay in relatively car-free areas while motor vehicles had clear paths to travel along.ConclusionThe results suggest that shared space, without large flowerpots, succeeded in inducing some uncertainty, especially among middle-aged and elderly pedestrians. However, deploying large flowerpots seemed to decrease this uncertainty, especially among elderly pedestrians. The major concern prompted by these results is how this decreased uncertainty affects traffic safety. Shared space also needs to be studied from the car driver’s perspective to understand the interaction between different road user groups.     

Investigating letter recognition in the brain by varying typeface: An event-related potential study

We aimed to investigate the contributions of visual letter form and abstract letter identity to the time course of letter recognition, by manipulating the typeface (i.e. font) in which letters were presented. Twenty-six adult participants completed a modified one-back task, where letters where presented in easy-to-read typefaces (“fluent” letter stimuli) or difficult-to-read typefaces (“disfluent” letter stimuli). Task instructions necessitated that participant’s focus on letter identity not visual letter form. Electroencephalography was collected and event-related potentials (ERPs) were calculated relative to letter stimuli. It was found that typeface affected both early-mid (N1 amplitude and P2–N2 amplitude and latency) and late processing (450–600 ms), thereby including time points whereby it is theorised that abstract identity is extracted from visual letter form (that is, 300 ms post-stimulus). Visual features of the letter therefore affect its processing well beyond the currently theorised point at which abstract information is extracted; which could be explained by a feedback loop between abstract letter representations and lower-level visual form processing units, which is not included in current cognitive reading models.     

On the empirical indistinguishability of knowledge structures

In recent years a number of articles have focused on the identifiability of the basic local independence model. The identifiability issue usually concerns two model parameter sets predicting an identical probability distribution on the response patterns. Both parameter sets are applied to the same knowledge structure. However, nothing is known about cases where different knowledge structures predict the same probability distribution. This situation is referred to as ʻempirical indistinguishabilityʼ between two structures and is the main subject of the present paper. Empirical indistinguishability is a stronger form of unidentifiability, which involves not only the parameters, but also the structural and combinatorial properties of the model. In particular, as far as knowledge structures are concerned, a consequence of empirical indistinguishability is that the existence of certain knowledge states cannot be empirically established. Most importantly, it is shown that model identifiability cannot guarantee that a certain knowledge structure is empirically distinguishable from others. The theoretical findings are exemplified in a number of different empirical scenarios.     

Effects of irrelevant object structure on early attention deployment

Event-related potential (ERP) studies have suggested that Gestalt principles or grouping factors in a visual scene modulate attention deployment in early visual processing. The present study examined the effects of an extrinsic grouping factor, region commonality, on early ERP spatial attention. Effects of sex were also explored, since the processing of task-irrelvant objects may differ between the sexes. Twenty-four participants were required to discriminate one side of rapidly-presented bilateral letters, and attention effects were indexed by hemispheric lateralization accroding to attended visual fields. In results, an early P1 attention effect (70–110 ms) increased when the letters were surrounded by an object, compared to the control stimulus without a complete object, and this result was more prominent in women than in men. The present study demonstrates that visual object and sex differences play a novel role at very early cortical stages of processing in attention deployment to a task-irrelevant visual structure.     

‘Place’, ‘space’ and ‘dialogue’: conceptualising dialogic spaciality in English faith-based universities

This article proposes a conceptualisation of dialogic spaciality, and advances our understandings of the dynamic interplay of dialogic space (where meaningful conversations take place) and place (a geographic location) and the influence these have on academic life. The conceptualisation is developed from a qualitative study which focused on the relationship of dialogue, space and intellectual encounters in faith-based higher education settings in England. The article highlights the significance of dialogue in these institutions because of the emphasis traditionally placed on conversation in the Christian university tradition. It concludes that dialogic spaciality may counter elements of non-reflexive and performative ethos as something that is transferable to other universities.     

内隐多效性选择的ERP证据

采用事件相关电位技术,考察内隐多效性选择及其神经机制。被试的任务是认真观看配对的纯色图片刺激,并进行分类按键反应。实验结果发现,在P2上,积极启动刺激比对照刺激激发了更大的P2波幅; 对比对照刺激,积极启动刺激在左脑、大脑中部和后脑诱发了更大的P2波幅,其中右脑的效应最大。在N2上,积极启动刺激比对照刺激激发了更小的N2波幅; 对比对照刺激,积极启动刺激在左脑、大脑中部和后脑诱发了更小的N2波幅,其中右脑的效应最大。在P3上,积极启动刺激比对照刺激激发了更大的P3波幅; 对比对照刺激,积极启动刺激在左脑、大脑中部和后脑诱发了更大的P3波幅,其中右脑的效应最大。研究结果表明当外显目标与内隐目标同时被呈现时,被试趋向于做多效性选择,这可能表明无意识信息加工具有相当大的权重。且右后部脑区可能是加工多效性刺激的核心和关键区域,P3成分可能反应了内隐多效性选择的精细加工过程,能够作为内隐多效性选择的有效的ERPs指标。     

Connecting the dots from a distance: Does mentally traveling through space and time increase searching for life’s meaning?

As humans, we have the ability to travel beyond the present moment by considering past and future times as well as locations that are distant from oneself. An interesting possibility is that such mental travel to far-away times and places (vs. focusing on times and places closer to the present) may increase people’s desire to search for their lives’ meaning. Since searching for meaning involves the integration of separate life events into a coherent life story, mentally traveling farther away from the present may make people aware that their life stories include more than what is happening at this very minute. Such awareness, then, may increase their desire to ‘connect the dots’ between their life events by searching for some underlying meaning. Three experiments (N = 838) tested this prediction and found that greater (vs. lower) mental travel through space or time increased the search for life’s meaning.