Examining Limits of Small Multiples: Frame Quantity Impacts Judgments with Line Graphs.

Small multiples are a popular visualization method, displaying different views of a dataset using multiple frames, often with the same scale and axes. However, there is a need to address their potential constraints, especially in the context of human cognitive capacity limits. These limits dictate the maximum information our mind can process at once. We explore the issue of capacity limitation by testing competing theories that describe how the number of frames shown in a display, the scale of the frames, and time constraints impact user performance with small multiples of line charts in an energy grid scenario. In two online studies (Experiment 1 n = 141 and Experiment 2 n = 360) and a follow-up eye-tracking analysis (n = 5), we found a linear decline in accuracy with increasing frames across seven tasks, which was not fully explained by differences in frame size, suggesting visual search challenges. Moreover, the studies demonstrate that highlighting specific frames can mitigate some visual search difficulties but, surprisingly, not eliminate them. This research offers insights into optimizing the utility of small multiples by aligning them with human limitations.

Numerical and Visual Representations of Uncertainty Lead to Different Patterns of Decision Making.

Although visualizations are a useful tool for helping people to understand information, they can also have unintended effects on human cognition. This is especially true for uncertain information, which is difficult for people to understand. Prior work has found that different methods of visualizing uncertain information can produce different patterns of decision making from users. However, uncertainty can also be represented via text or numerical information, and few studies have systematically compared these types of representations to visualizations of uncertainty. We present two experiments that compared visual representations of risk (icon arrays) to numerical representations (natural frequencies) in a wildfire evacuation task. Like prior studies, we found that different types of visual cues led to different patterns of decision making. In addition, our comparison of visual and numerical representations of risk found that people were more likely to evacuate when they saw visualizations than when they saw numerical representations. These experiments reinforce the idea that design choices are not neutral: seemingly minor differences in how information is represented can have important impacts on human risk perception and decision making.

Studying visual search without an eye tracker: an assessment of artificial foveation.

Eye tracking is a useful tool for studying human cognition, both in the laboratory and in real-world applications. However, there are cases in which eye tracking is not possible, such as in high-security environments where recording devices cannot be introduced. After facing this challenge in our own work, we sought to test the effectiveness of using artificial foveation as an alternative to eye tracking for studying visual search performance. Two groups of participants completed the same list comparison task, which was a computer-based task designed to mimic an inventory verification process that is commonly performed by international nuclear safeguards inspectors. We manipulated the way in which the items on the inventory list were ordered and color coded. For the eye tracking group, an eye tracker was used to assess the order in which participants viewed the items and the number of fixations per trial in each list condition. For the artificial foveation group, the items were covered with a blurry mask except when participants moused over them. We tracked the order in which participants viewed the items by moving their mouse and the number of items viewed per trial in each list condition. We observed the same overall pattern of performance for the various list display conditions, regardless of the method. However, participants were much slower to complete the task when using artificial foveation and had more variability in their accuracy. Our results indicate that the artificial foveation method can reveal the same pattern of differences across conditions as eye tracking, but it can also impact participants' task performance.

Where are we going and where have we been? Examining the effects of maps on spatial learning in an indoor guided navigation task.

BACKGROUND: International Atomic Energy Agency (IAEA) safeguards inspectors are faced with the difficult task of learning the layout of complex nuclear facilities while being escorted through the facilities. This study addresses a gap in the literature regarding how to best support the development of inspectors' spatial knowledge, given the constraint that they cannot bring digital devices into most nuclear facilities. We tested whether viewing a map before learning a guided route or carrying a map along the route enabled better spatial learning than having no exposure to a map. Moreover, we tested the impact of carrying maps with different levels of detail (simple 2D, simple 3D, or complex 2D maps) on spatial learning outcomes, as well as interactions between map type and individual differences in sense of direction. RESULTS: The results showed nearly opposite patterns of performance for participants with good and poor sense of direction scores. Participants with a good sense of direction showed higher levels of spatial knowledge when studying or carrying simple maps, whether 2D or 3D, but they did not benefit from using a complex map. Participants with a poor sense of direction showed lower levels of spatial knowledge when using a simple map relative to using no map or a complex map, suggesting that they did not attempt to use the complex map. For both groups of participants, referring to a simple map while learning a route decreased their awareness of their environment, as measured by response times on a memory test that included incidentally learned items.

Differential Age Effects of Transcranial Direct Current Stimulation on Associative Memory.

OBJECTIVES: Older adults experience associative memory deficits relative to younger adults (Old & Naveh-Benjamin, 2008). The aim of this study was to test the effect of transcranial direct current stimulation (tDCS) on face-name associative memory in older and younger adults. METHOD: Experimenters applied active (1.5 mA) or sham (0.1 mA) stimulation with the anode placed over the left dorsolateral prefrontal cortex (dlPFC) during a face-name encoding task, and measured both cued recall and recognition performance. Participants completed memory tests immediately after stimulation and after a 24-h delay to examine both immediate and delayed stimulation effects on memory. RESULTS: Results showed improved face-name associative memory performance for both recall and recognition measures, but only for younger adults, whereas there was no difference between active and sham stimulation for older adults. For younger adults, stimulation-induced memory improvements persisted after a 24-h delay, suggesting delayed effects of tDCS after a consolidation period. DISCUSSION: Although effective in younger adults, these results suggest that older adults may be resistant to this intervention, at least under the stimulation parameters used in the current study. This finding is inconsistent with a commonly seen trend, where tDCS effects on cognition are larger in older than younger adults.

Data Visualization Saliency Model: A Tool for Evaluating Abstract Data Visualizations.

Evaluating the effectiveness of data visualizations is a challenging undertaking and often relies on one-off studies that test a visualization in the context of one specific task. Researchers across the fields of data science, visualization, and human-computer interaction are calling for foundational tools and principles that could be applied to assessing the effectiveness of data visualizations in a more rapid and generalizable manner. One possibility for such a tool is a model of visual saliency for data visualizations. Visual saliency models are typically based on the properties of the human visual cortex and predict which areas of a scene have visual features (e.g. color, luminance, edges) that are likely to draw a viewer's attention. While these models can accurately predict where viewers will look in a natural scene, they typically do not perform well for abstract data visualizations. In this paper, we discuss the reasons for the poor performance of existing saliency models when applied to data visualizations. We introduce the Data Visualization Saliency (DVS) model, a saliency model tailored to address some of these weaknesses, and we test the performance of the DVS model and existing saliency models by comparing the saliency maps produced by the models to eye tracking data obtained from human viewers. Finally, we describe how modified saliency models could be used as general tools for assessing the effectiveness of visualizations, including the strengths and weaknesses of this approach.

Transcranial direct current stimulation of dorsolateral prefrontal cortex during encoding improves recall but not recognition memory.

Prior work demonstrates that application of transcranial direct current stimulation (tDCS) improves memory. In this study, we investigated tDCS effects on face-name associative memory using both recall and recognition tests. Participants encoded face-name pairs under either active (1.5mA) or sham (.1mA) stimulation applied to the scalp adjacent to the left dorsolateral prefrontal cortex (dlPFC), an area known to support associative memory. Participants' memory was then tested after study (day one) and then again after a 24-h delay (day two), to assess both immediate and delayed stimulation effects on memory. Results indicated that active relative to sham stimulation led to substantially improved recall (more than 50%) at both day one and day two. Recognition memory performance did not differ between stimulation groups at either time point. These results suggest that stimulation at encoding improves memory performance by enhancing memory for details that enable a rich recollective experience, but that these improvements are evident only under some testing conditions, especially those that rely on recollection. Overall, stimulation of the dlPFC could have led to recall improvement through enhanced encoding from stimulation or from carryover effects of stimulation that influenced retrieval processes, or both.

Enhanced working memory performance via transcranial direct current stimulation: The possibility of near and far transfer.

Although working memory (WM) training programs consistently result in improvement on the trained task, benefit is typically short-lived and extends only to tasks very similar to the trained task (i.e., near transfer). It is possible that pairing repeated performance of a WM task with brain stimulation encourages plasticity in brain networks involved in WM task performance, thereby improving the training benefit. In the current study, transcranial direct current stimulation (tDCS) was paired with performance of a WM task (n-back). In Experiment 1, participants performed a spatial location-monitoring n-back during stimulation, while Experiment 2 used a verbal identity-monitoring n-back. In each experiment, participants received either active (2.0mA) or sham (0.1mA) stimulation with the anode placed over either the right or the left dorsolateral prefrontal cortex (DLPFC) and the cathode placed extracephalically. In Experiment 1, only participants receiving active stimulation with the anode placed over the right DLPFC showed marginal improvement on the trained spatial n-back, which did not extend to a near transfer (verbal n-back) or far transfer task (a matrix-reasoning task designed to measure fluid intelligence). In Experiment 2, both left and right anode placements led to improvement, and right DLPFC stimulation resulted in numerical (though not sham-adjusted) improvement on the near transfer (spatial n-back) and far transfer (fluid intelligence) task. Results suggest that WM training paired with brain stimulation may result in cognitive enhancement that transfers to performance on other tasks, depending on the combination of training task and tDCS parameters used.

Practice makes imperfect: Working memory training can harm recognition memory performance.

There is a great deal of debate concerning the benefits of working memory (WM) training and whether that training can transfer to other tasks. Although a consistent finding is that WM training programs elicit a short-term near-transfer effect (i.e., improvement in WM skills), results are inconsistent when considering persistence of such improvement and far transfer effects. In this study, we compared three groups of participants: a group that received WM training, a group that received training on how to use a mental imagery memory strategy, and a control group that received no training. Although the WM training group improved on the trained task, their posttraining performance on nontrained WM tasks did not differ from that of the other two groups. In addition, although the imagery training group's performance on a recognition memory task increased after training, the WM training group's performance on the task decreased after training. Participants' descriptions of the strategies they used to remember the studied items indicated that WM training may lead people to adopt memory strategies that are less effective for other types of memory tasks. These results indicate that WM training may have unintended consequences for other types of memory performance.

Transcranial stimulation over the left inferior frontal gyrus increases false alarms in an associative memory task in older adults.

BACKGROUND: Transcranial direct current stimulation (tDCS) is a potential tool for alleviating various forms of cognitive decline, including memory loss, in older adults. However, past effects of tDCS on cognitive ability have been mixed. One important potential moderator of tDCS effects is the baseline level of cognitive performance. METHODS: We tested the effects of tDCS on face-name associative memory in older adults, who suffer from performance deficits in this task relative to younger adults. Stimulation was applied to the left inferior prefrontal cortex during encoding of face-name pairs, and memory was assessed with both a recognition and recall task. RESULTS: Face-name memory performance was decreased with the use of tDCS. This result was driven by increased false alarms when recognizing rearranged face-name pairs. CONCLUSIONS: This result suggests that tDCS can lead to increased false alarm rates in recognition memory, and that effects of tDCS on a specific cognitive task may depend upon cognitive capability for that task.

Effects of non-invasive brain stimulation on associative memory.

Associative memory refers to remembering the association between two items, such as a face and a name. It is a crucial part of daily life, but it is also one of the first aspects of memory performance that is impacted by aging and by Alzheimer's disease. Evidence suggests that transcranial direct current stimulation (tDCS) can improve memory performance, but few tDCS studies have investigated its impact on associative memory. In addition, no prior study of the effects of tDCS on memory performance has systematically evaluated the impact of tDCS on different types of memory assessments, such as recognition and recall tests. In this study, we measured the effects of tDCS on associative memory performance in healthy adults, using both recognition and recall tests. Participants studied face-name pairs while receiving either active (30 min, 2 mA) or sham (30 min, 0.1 mA) stimulation with the anode placed at F9 and the cathode placed on the contralateral upper arm. Participants in the active stimulation group performed significantly better on the recall test than participants in the sham group, recalling 50% more names, on average, and making fewer recall errors. However, the two groups did not differ significantly in terms of their performance on the recognition memory test. This investigation provides evidence that stimulation at the time of study improves associative memory encoding, but that this memory benefit is evident only under certain retrieval conditions.

Older and wiser: older adults' episodic word memory benefits from sentence study contexts.

A hallmark of adaptive cognition is the ability to modulate learning in response to the demands posed by different types of tests and different types of materials. Here we evaluate how older adults process out-of-context words and sentences differently by examining patterns of memory errors. In two experiments, we explored younger and older adults' sensitivity to lures on a recognition test following study of words in these two types of contexts. Among the studied words were compound words such as "blackmail" and "jailbird" that were related to conjunction lures (e.g., "blackbird") and semantic lures (e.g., "criminal"). Participants engaged in a recognition test that included old items, conjunction lures, semantic lures, and unrelated new items. In both experiments, younger and older adults had the same general pattern of memory errors: more incorrect endorsements of semantic than conjunction lures following sentence study and more incorrect endorsements of conjunction than semantic lures following list study. The similar pattern reveals that older and younger adults responded to the constraints of the two different study contexts in similar ways. However, although younger and older adults showed similar levels of memory performance for the list study context, the sentence study context elicited superior memory performance in the older participants. It appears as though memory tasks that take advantage of greater expertise in older adults--in this case, greater experience with sentence processing--can reveal superior memory performance in the elderly.

Tests of the DRYAD theory of the age-related deficit in memory for context: not about context, and not about aging.

Older adults exhibit a disproportionate deficit in their ability to recover contextual elements or source information about prior encounters with stimuli. A recent theoretical account, DRYAD, attributes this selective deficit to a global decrease in memory fidelity with age, moderated by weak representation of contextual information. The predictions of DRYAD are tested here in three experiments. We show that an age-related deficit obtains for whichever aspect of the stimulus subjects' attention is directed away from during encoding (Experiment 1), suggesting a central role for attention in producing the age-related deficit in context. We also show that an analogous deficit can be elicited within young subjects with a manipulation of study time (Experiment 2), suggesting that any means of reducing memory fidelity yields an interaction of the same form as the age-related effect. Experiment 3 evaluates the critical prediction of DRYAD that endorsement probability in an exclusion task should vary nonmonotonically with memory strength. This prediction was confirmed by assessing the shape of the forgetting function in a continuous exclusion task. The results are consistent with the DRYAD account of aging and memory judgments and do not support the widely held view that aging entails the selective disruption of processes involved in encoding, storing, or retrieving contextual information.

Contributions of familiarity and recollection rejection to recognition: evidence from the time course of false recognition for semantic and conjunction lures.

It has been suggested that both familiarity and recollection contribute to the recognition decision process. In this paper we leverage the form of false alarm rate functions--in which false alarm rates describe an inverted U-shaped function as the time between study and test increases--to assess how these processes support retention of semantic and surface form information from previously studied words. We directly compare the maxima of these functions for lures that are semantically related and lures that are related by surface form to previously studied material. This analysis reveals a more rapid loss of access to surface form than to semantic information. To separate the contributions of item familiarity and reminding-induced recollection rejection to this effect, we use a simple multinomial process model; this analysis reveals that this loss of access reflects both a more rapid loss of familiarity and lower rates of recollection for surface form information.

Recreating Raven's: software for systematically generating large numbers of Raven-like matrix problems with normed properties.

Raven's Progressive Matrices is a widely used test for assessing intelligence and reasoning ability (Raven, Court, & Raven, 1998). Since the test is nonverbal, it can be applied to many different populations and has been used all over the world (Court & Raven, 1995). However, relatively few matrices are in the sets developed by Raven, which limits their use in experiments requiring large numbers of stimuli. For the present study, we analyzed the types of relations that appear in Raven's original Standard Progressive Matrices (SPMs) and created a software tool that can combine the same types of relations according to parameters chosen by the experimenter, to produce very large numbers of matrix problems with specific properties. We then conducted a norming study in which the matrices we generated were compared with the actual SPMs. This study showed that the generated matrices both covered and expanded on the range of problem difficulties provided by the SPMs.

Remembering words not presented in sentences: how study context changes patterns of false memories.

People falsely endorse semantic associates and morpheme rearrangements of studied words at high rates in recognition testing. The coexistence of these results is paradoxical: Models of reading that presume automatic extraction of meaning cannot account for elevated false memory for foils that are related to studied stimuli only by their visual form; models without such a process cannot account for false memory for semantic foils. Here we show how sentence and list study contexts encourage different encoding modes and consequently lead to different patterns of memory errors. Participants studied compound words, such as tailspin and floodgate, as single words or embedded in sentences. We show that sentence contexts led subjects to be better able to discriminate conjunction lures (e.g., tailgate) from old words than did list contexts. Conversely, list contexts led to superior discrimination of semantic lures (e.g., nosedive) from old words than did sentence contexts.