Aging and enumeration: a selective deficit for the subitization of targets among distractors

The term subitization has been used to refer to the fast and accurate enumeration of up to about 4 items. Beyond 4 items, enumeration becomes more serial and less accurate, with each additional item adding to the total enumeration time. The effects of aging on visual enumeration of targets (Os) were assessed with and without the presence of distractors (Xs). Young participants (n = 30; 18-27 years) showed the usual subitization-counting enumeration function, both with and without the presence of distractors. In contrast, for older participants (n = 35; 65-79 years), evidence for subitization was found only when distractors were absent. This occurred even though they could detect an individual target among distractors in parallel across the field. The results are discussed in relation to recent theories of visual selection and enumeration.     

Search, enumeration, and aging: eye movement requirements cause age-equivalent performance in enumeration but not in search tasks

Response time (RT) and fixation frequency were measured for young and older adults in search and enumeration tasks under high- and low-attentional competition conditions. There was an age-related decrement in search rates for single targets both for RT and fixation frequency, but there was no deficit in enumeration rates either with or without distractors even though serial enumeration rates were much slower than single target search rates. Fixation frequency per item in serial enumeration was much greater than in serial visual search for a single target. Enumerating targets with distractors produced an overall increase in RT and fixation frequency that was greater for older adults. The data are contrary to a generalized slowing account, and an alternative is proposed on the basis of the need to make eye movements in enumeration but not in search tasks.     

Older and younger adults' strategies in approximate quantification

In two experiments, participants were asked to provide a quick and rough estimate of the number of items in collections of 4-79 items. In Experiment 1 verbal strategy reports and performance on each item were collected, and in Experiment 2 performance and eye movements were collected, while young and older participants were tested in strategy-instructed conditions. Results showed that: (a) participants used six different estimation strategies, (b) overall, young and older participants used the same set of strategies, but varied in how often they used each strategy, (c) older adults' strategy repertoire was smaller than young adults' (i.e., inter-individual differences in strategy repertoire), (d) strategy use, participants' performance, and eye movements varied as a function of numerosities and configurations of items, (e) in both the age groups, each strategy was associated with distinctive performance measures and eye movement patterns. These findings show that different processes are available for approximate quantification in both young and older adults and that aging is associated with strategic variations.     

Subitizing and counting depend on different attentional mechanisms: Evidence from visual enumeration in afterimages

Two experiments showed that, when selective eye movements were disabled by the presentation of stimuli in the form of afterimages, increased inspection time and facilitative stimulus configurations failed to increase the subitizing limit of 4 objects. Afterimages of two to eight dots induced by a photographic flashgun were shown to 3 adult subjects. For more than 4 objects, enumeration errors occurred at a rate of 20%–30%. Enumeration was effectively perfect for 2–4 linearly configured dots, with occasional errors surprisingly occurring in that range when dots appeared in groups of up to 3 items. No errors occurred in nonafterimage control conditions. Enumeration errors were attributed to failures of individuating dots to be counted due to the deactivation of selective eye movements in afterimages. A third experiment supported this interpretation by disabling eye movements with briefly presented stimuli and producing results much like those of the afterimage conditions.     

Saccades elicit obligatory allocation of visual working memory

In daily life, visual working memory (VWM) typically works in contexts in which people make frequent saccades. Here, we investigated whether people can effectively control the allocation of VWM when making a saccade. Subjects were required to make an intervening saccade in the process of a memory task. The saccade target was either a to-be-remembered item or an extra, not-to-be-remembered item. The results showed that memory performance was poorer when a saccade was made to the extra, not-to-be-remembered item, regardless of its similarity to the memory item(s). In contrast, when memorizing the items while remaining fixated, subjects had similar memory performance whether an extra, not-to-be-remembered item was present or not. Taken together, these results demonstrated that volitional control over VWM allocation is greatly impaired when a saccade is made, indicating that VWM contains an automatic part that cooperates with eye movements and is allocated to a saccade target obligatorily.     

比较视觉搜索任务的认知老化研究

本研究通过增加组成图片的图形数量和改变目标图形的特征,考察老年人和大学生在比较视觉搜索任务中的眼动特点和图形特征加工的优先性。结果表明与青年人相比,老年人在比较视觉搜索过程中总注视时间和注视次数增加,平均眼跳幅度减少,对目标刺激的注视时间增加。老年人和青年人在目标刺激的注视过程中都表现出图形维度数量的优先性,即表现为颜色和形状都不同的目标刺激注视时间最短,颜色不同和形状不同的目标刺激在注视时间上差异不显著。说明老年人在比较视觉搜索过程中存在认知老化,在图形特征加工的优先性上结果和青年人一致,以上结果与年龄和研究任务有关。     

Simultaneous processing of visual information and planning of hand movements in a visuo-manual search task

When searching for a target with eye movements, saccades are planned and initiated while the visual information is still being processed. If hand movements are needed to perform a search task, can they too be planned while visual information from the current position is still being processed? To find out we studied a visual search task in which participants had to move their hand to shift a window through which they could see the items. The task was to find an O in a circle of Cs. The size of the window and the sizes of the gaps in the Cs were varied. Participants made fast, smooth arm movements between items and adjusted their movements, when on the items, to the window size. On many trials the window passed the target and returned, indicating that the next movement had been planned before identifying the item that was in view.     

Salience drives overt selection of two equally relevant visual targets

In the present study, we investigated whether salience determines the sequence of selection when participants search for two equally relevant visual targets. To do this, attentional selection was tracked overtly as observers inspected two items of differing physical salience: one a highly salient color singleton, and the other a less salient shape singleton. Participants were instructed to make natural eye movements in order to determine whether two line segments contained within the two singletons were oriented in the same or in different directions. Because both singleton items were task-relevant, participants had no reason to inspect one item before the other. As expected, observers fixated both targets on the majority of trials. Critically, saccades to the color singleton preceded saccades to the less salient shape singleton on the majority of trials. This demonstrates that the order of attentional object selection is largely determined by stimulus salience when task relevance is equated.     

Carryover of scanning behaviour affects upright face recognition differently to inverted face recognition

Face perception is characterized by a distinct scanpath. While eye movements are considered functional, there has not been direct evidence that disrupting this scanpath affects face recognition performance. The present experiment investigated the influence of an irrelevant letter-search task (with letter strings arranged horizontally, vertically, or randomly) on the subsequent scanning strategies in processing upright and inverted famous faces. Participants’ response time to identify the face and the direction of their eye movements were recorded. The orientation of the letter search influenced saccadic direction when viewing the face images, such that a direct carryover-effect was observed. Following a vertically oriented letter-search task, the recognition of famous faces was slower and less accurate for upright faces, and faster for inverted faces. These results extend the carryover findings of Thompson and Crundall into a novel domain. Crucially they also indicate that upright and inverted faces are better processed by different eye movements, highlighting the importance of scanpaths in face recognition.     

Age differences in enumerating things that move: Implications for the development of multiple-object tracking

The attentional theory of spatial enumeration (Trick & Pylyshyn, 1994) predicts that subitizing, the rapid process (40-120 msec/item) used to enumerate 1-4 items, employs the same mechanism that permits individuals to track 4-5 moving items simultaneously, whereas enumerating more items requires moving attentional focus from area to area in the display. To test this theory, enumeration of static and moving items was investigated in 8-, 10-, 12-, and 20-year-old participants using a number discrimination task. As was predicted, random independent item motion did not substantially impede enumeration of 1-4 items regardless of age. However, even movement within a 1.14 degree square area slowed enumeration of 6-9 items, although on average the interference decreased with age from 788 msec for the 8-year-olds to 136 msec for the 20-year-olds. The relevance of this finding for theories of enumeration, multiple-object tracking, visual working memory, and object-based attention is discussed.     

The form of the information and selective counting by ESN(M) pupils

The study springs from views on attentional deficits in retarded performers. Three experiments are reported in which educationally sub-normal (mild) category pupils and average ability pupils matched with them for mental age perform a speeded classification of cards on the basis of an enumeration of a group of items on each card. This group may be the total of the items on the card or a selected part of that total. Interest focuses upon the relationship between performance in the selective situation and the form or structure of the item group. It is argued initially that attentional patterns may be expected to vary in relation to the specific structure of the information available and the way the performer appreciates that structure. The results support this notion. ESN(M) subjects perform in a similar fashion to the matched group, even given selective instructions, when what must be counted is the whole of a vertical linear series of items. However, when what must be counted is in the form of a part of a vertical linear item series, the performance of the ESN(M) group is significantly slower than that of the matched group. In addition the matched group appear more sensitive to discontinuity within the vertical item series while the ESN(M) group may have a less differentiated approach to such information founded mainly on the appreciation of verticality. It is suggested that aspects of information available to performers must be studied in relation to the kind of whole the particular performer takes the information to be. Although retardates do not carry appropriate structural expectations from situation to situation, suitable organisation of information can be appreciated, leading to more successful performance.     

Enumeration: shape information and expertise

This study examined the interaction between grouping information and expertise in a simple enumeration task. In two experiments, participants made rapid judgements about the number of items present in a visual display. Within each display, items were grouped into a canonical representation (e.g., triangle, square, and pentagon) or were arranged linearly. In both experiments, grouping information facilitated enumeration performance, replicating previous findings in the literature. In Experiment 2, the facilitative effect of grouping information was found to be greater for Air Traffic Controllers (ATCs) than for matched novices, though they were no better than novices on linear arrays. This may be because linear, like canonical arrays, hold unique numerosity information, but only when they contain the minimum number of points necessary to define a line (i.e., 2). So ATCs' performance on linear arrays containing more than two items does not benefit from a facilitative effect of grouping information. That their experience of being ATCs, in terms of years served, was shown to account for the expertise effect suggests that such visuospatial expertise is acquired through frequent exposure to spatial arrays.     

Assessing the Robustness of Mixture Models to Measurement Noninvariance

Abstract

Recent work reframes direct effects of covariates on items in mixture models as differential item functioning (DIF) and shows that, when present in the data but omitted from the fitted latent class model, DIF can lead to overextraction of classes. However, less is known about the effects of DIF on model performance—including parameter bias, classification accuracy, and distortion of class-specific response profiles—once the correct number of classes is chosen. First, we replicate and extend prior findings relating DIF to class enumeration using a comprehensive simulation study. In a second simulation study using the same parameters, we show that, while the performance of LCA is robust to the misspecification of DIF effects, it is degraded when DIF is omitted entirely. Moreover, the robustness of LCA to omitted DIF differs widely based on the degree of class separation. Finally, simulation results are contextualized by an empirical example.     

Interference between maintenance and processing in working memory: the effect of item-distractor similarity in complex span

Four experiments examined the effect of phonological similarity between items and distractors on complex span performance. Item-distractor similarity benefited serial recall when distractors followed the items they were similar to, but not when distractors preceded the items they were similar to. These findings are predicted by C-SOB (contextual serial order in a box), a computational model of complex span. The model assumes that distractors are involuntarily encoded into memory, being associated to the preceding item's list position. Distractors interfere with items by superposition of distributed representations that are associated to the same position. Superposition distorts item memory; this distortion is less severe when the distractor is similar to the item. Further support for the assumption that distractors are encoded at the position of the preceding item comes from the finding that intrusions of distractors at recall tended to come from the position of the target item. In addition, intruding distractors tend to replace items to which they are similar, showing that lack of distinctiveness also contributes to interference.     

Implicit and explicit memory without awareness

Summary Three experiments are reported which investigate the conscious status of subjects during an implicit-memory test. In all experiments the subjects either named each visually presented target item or generated each item from an anagram in a first phase of incidental learning. In a second phase, they were either given a visual word-stem completion task as an implicit-memory test or given a recognition task (Experiment 1), or a cued-recall task (Experiments 2 and 3) as explicit-memory tests. Finally, in a third phase the subjects were required to make decisions about the input status (i. e., they had to decide whether the item was present in the first phase) as well as about the output status of information (i. e., they had to decide whether the item had been completed, recognized or recalled in the second phase). A generation effect (i. e., generated items were remembered better than named items) was evident in the recognition and recall data, but only for items whose recognition or recall was accompanied by conscious recollection of their previous occurrence in the study list. Judgments about the input status were more precise, given that items had been consciously recognized or recalled rather than completed. The same pattern of findings was observed for judgments about the output status. The results are interpreted as evidence that subjects in implicit-memory tests are less aware of the fact that some of their productions are relevant to prior experiences. In addition, they are less aware of the fact that they are retrieving information from their memories. However, the same state of nonawareness may be present in explicit-memory tests, as was revealed by the performance of subjects on those items whose recognition or recall was not accompanied by conscious recollection.     

Adaptive reasoning: Componential and eye movement analysis of geometric analogy performance

The present study explored individual differences in performance of a geometric analogies task. Whereas past studies employed true/false or two-alternative items, the present research included four-alternative items and studied eye movements and confidence judgements for each item performance as well as latency and error. Item difficulty proved to be a function of an interaction between the number of response alternatives and the number of elements in items, especially for subjects lower in fluid-analytic reasoning ability. Results were interpreted using two hypothesized performance strategies: constructive matching and response elimination. The less efficient of these, response elimination, seemed to be used more by lower ability subjects on more difficult items. While two previous theories resemble one or the other of these strategies, neither alone seems to capture the complexity of adaptive problem solving. It appears that a comprehensive theory should incorporate strategy shifting as a function of item difficulty and subject ability.Componential models, based in part on past research, revealed that a justification component was activated and deactivated depending upon the nature of the analogy being solved. In addition, two new components, spatial inference and spatial application, were identified as important on some items, suggesting that different geometric analogy items invoke different cognitive processing components. Thus, a comprehensive theory should also describe component activation and deactivation.     

Metamemory and reality monitoring

Metamemory judgements and reality monitoring judgements were compared for real and imagined stimuli. Line drawings of everyday items were either perceived or imagined in differing ratios, to (a) investigate people's ability to predict the class of item that would be better recalled (Judgements of Learning, JOL), and the class of item which would be better sourced (Judgements of Source, JOS) in a future recall test, and (b) test the hypothesis that participants would show a bias towards calling remembered items real when the source had been forgotten. Although participants' JOLs indicated that they believed real items would be more memorable than imagined, in both experiments a larger proportion of items from either class (real or imagined) was only recalled when presentation modality was less frequent for that class. By contrast, JOSs were no different for real or imagined items, even though source attribution was more accurate for real than imagined items. An attribution of memories to real rather than to imagined events that often occurs when participants are unsure about the source (labelled a ‘bias towards the real’) was due to phenomenological qualities of the memories. The results are discussed in terms of Johnson and Raye's ( 1981 ) reality‐monitoring model. Copyright © 2002 John Wiley & Sons, Ltd.     

The eyes know what you are thinking: eye movements as an objective measure of mind wandering

Paralleling the recent work by Reichle, Reineberg, and Schooler (2010), we explore the use of eye movements as an objective measure of mind wandering while participants performed a reading task. Participants were placed in a self-classified probe-caught mind wandering paradigm while their eye movements were recorded. They were randomly probed every 2–3 min and were required to indicate whether their mind had been wandering. The results show that eye movements were generally less complex when participants reported mind wandering episodes, with both duration and frequency of within-word regressions, for example, becoming significantly reduced. This is consistent with the theoretical claim that the cognitive processes that normally influence eye movements to enhance semantic processing during reading exert less control during mind wandering episodes.     

Horizontal saccadic eye movements enhance the retrieval of landmark shape and location information

Recent work has demonstrated that horizontal saccadic eye movements enhance verbal episodic memory retrieval, particularly in strongly right-handed individuals. The present experiments test three primary assumptions derived from this research. First, horizontal eye movements should facilitate episodic memory for both verbal and non-verbal information. Second, the benefits of horizontal eye movements should only be seen when they immediately precede tasks that demand right and left-hemisphere processing towards successful performance. Third, the benefits of horizontal eye movements should be most pronounced in the strongly right-handed. Two experiments confirmed these hypotheses: horizontal eye movements increased recognition sensitivity and decreased response times during a spatial memory test relative to both vertical eye movements and fixation. These effects were only seen when horizontal eye movements preceded episodic memory retrieval, and not when they preceded encoding (Experiment 1). Further, when eye movements preceded retrieval, they were only beneficial with recognition tests demanding a high degree of right and left-hemisphere activity (Experiment 2). In both experiments the beneficial effects of horizontal eye movements were greatest for strongly right-handed individuals. These results support recent work suggesting increased interhemispheric brain activity induced by bilateral horizontal eye movements, and extend this literature to the encoding and retrieval of landmark shape and location information.     

Comparing target detection errors in visual search and manually-assisted search

Subjects searched for low- or high-prevalence targets among static nonoverlapping items or items piled in heaps that could be moved using a computer mouse. We replicated the classical prevalence effect both in visual search and when unpacking items from heaps, with more target misses under low prevalence. Moreover, we replicated our previous finding that while unpacking, people often move the target item without noticing (the unpacking error) and determined that these errors also increase under low prevalence. On the basis of a comparison of item movements during the manually-assisted search and eye movements during static visual search, we suggest that low prevalence leads to broadly reduced diligence during search but that the locus of this reduced diligence depends on the nature of the task. In particular, while misses during visual search often arise from a failure to inspect all of the items, misses during manually-assisted search more often result from a failure to adequately inspect individual items. Indeed, during manually-assisted search, over 90 % of target misses occurred despite subjects having moved the target item during search.