Iconic memory for natural scenes: Evidence using a modified change-detection procedure

ABSTRACT

Change blindness for the contents of natural scenes suggests that only items that are attended while the scene is still visible are stored, leading some to characterize our visual experiences as sparse. Experiments on iconic memory for arrays of discrete symbols or objects, however, indicate observers have access to more visual information for at least several hundred milliseconds at offset of a display. In the experiment presented here, we demonstrate an iconic memory for complex natural or real-world scenes. Using a modified change detection task in which to-be changed objects are cued at offset of the scene, we show that more information from a natural scene is briefly stored than change blindness predicts and more than is contained in visual short-term memory. In our experiment, a cue appearing 0, 300, or 1000?msec after offset of the pre-change scene or at onset of the second scene presentation (a Post Cue) directed attention to the location of a possible change. Compared to a no-cue condition, subjects were significantly better at detecting changes and identifying what changed in the cue condition, with the cue having a diminishing effect as a function of time and no effect when its onset coincided with that of the second scene presentation. The results suggest that an iconic memory of a natural scene exists for at least 1000?msec after scene offset, from which subjects can access the identity of items in the pre-change scene. This implies that change blindness underestimates the amount of information available to the visual system from a brief glance of a natural scene.     

Does driving experience in video games count? Hazard anticipation and visual exploration of male gamers as function of driving experience

Risk perception and distribution of visual attention while driving are crucial elements for accident prevention and new-driver improvement. This study investigates how racing videogames could shape the visual exploration of virtual and real road in male pre-drivers. The visual performance of players of racing video games with and without driver’s license was tested in virtual vs. real scenarios. Attention to specific elements of different types of road interactions was monitored using an eye-tracking system. Results showed that habitual use of racing video games was not found to foster a positive effect on users’ distribution of visual attention, supporting visual patterns typical of novice drivers. Gamers without driving experience replicated the same patterns in a real road scenario, ignoring road signs and potential areas of interactions with other drivers, while experienced drivers gamers explored video games roads like real roads. The fact that the gamers’ driving performance was not comparable to drivers in the virtual scenario suggests that there are other variables in the gameplay that create a less complex traffic scene, still the visual complexity of different real road interactions is kept in video game interactions, opening new perspectives towards gamers’ visual exploration of the road.     

Toupee or not toupee? The role of instructional set,centrality, and relevance in change blindness

The influence of instructional set, centrality, and relevance on change blindness was examined. In a one-shot paradigm, participants reported alterations of items across pairs of driving scenes under two different instructional conditions. Alterations involved either relocations or disappearances of the same items and included driving-relevant and driving-irrelevant alterations to items of central and marginal interest. Three main findings emerged: Centrality was not a function of driving relevance/meaningfulness, disappearances of central interest items were identified significantly more often than positional changes to them, and instructions highlighting the importance of the task to driving attenuated change blindness. The possible role of a simple listing strategy in mediating successful identification of alterations is discussed. Together, the findings demonstrate that cognitive factors play an important role in change blindness.     

影响驾驶安全的驾驶员注意模式研究述评

驾驶员的视觉注意模式对于汽车安全驾驶具有非常重要的意义。本文主要从驾驶员的路面视觉扫描模式和整体视觉场景的注意模式两个方面对国内外有关研究进行了概览。主要包括: (1)视觉扫描模式对驾驶安全的影响研究; (2)驾驶员视觉注意分配模型研究; (3)以及针对驾驶员视觉扫描模式的培训研究。并提出进一步研究有待于深入探讨影响驾驶员视觉注意模式的影响因素以及开展适合我国汽车驾驶特点的本土化研究。     

The effect of leftward bias on visual attention for driving tasks

The leftward bias of driving visual attention has been found to explain the role of driving experience in the visual attention strategy; even though the results reported in the literature are not always consistent. This study aims to explore the driving attention characteristics and the eye movement patterns by using a simulated driving experiment in conjunction with an eye-tracker device. 31 young inexperienced drivers (undergraduate students, average age 21) and 30 old experienced drivers (taxi drivers, average age 36) took part in the experiment. Results show that the eye movement patterns of the drivers have certain similarity in the occurrence of subtle asymmetries of visual attention favouring left space (the direction of the driving in the experiment was right-side) and that they are related to the right hemisphere specialization for spatial attention. However, in the more experienced drivers the leftward eye movement tends to shift toward the centre or even rightward to pay attention to the hazard events on road. These results suggest that inexperienced drivers are initially aroused by natural biological leftward visual attention and likely to develop central and rightward eye movement strategy for safety diving purpose. The implications of this study suggest that, despite the existence of natural visual attention bias, the left asymmetries in visual scan in inexperienced drivers still can be modified by driving trainings that focus on the hazard situation on road.     

Impact of Relevance and Distraction on Driving Performance and Visual Attention in a Simulated Driving Environment

Previous demonstrations of the impact of cellular phone conversations on visual attention when driving have primarily focused on attention to stimuli that are not relevant to driving. In contrast, we used a driving simulator and eye tracking to examine attention allocation across driving‐relevant and driving‐irrelevant items in the environment depending on whether drivers were distracted. Performance measures indicated that distraction negatively impacted vehicle control. However, driving relevance and the presence of distraction did not interact, suggesting that participants responded to potential hazards similarly in driving‐only and distraction conditions. In contrast, eye movement results indicated an interaction between distraction and relevance. Drivers attended more to driving‐relevant objects, and these objects showed smaller decrements in number of gazes in the distraction condition, compared with less relevant items. Even under distraction conditions, experienced drivers continued to attend to potential hazards, allocating less attention to billboards and roadway signage. Copyright © 2013 John Wiley & Sons, Ltd.     

驾驶员在交通场景中的变化视盲及其启示

变化视盲(change blindness)现象,也称变化盲,是指视觉情景中人们不能觉察到某个事物变化的现象。研究以驾驶员为主体探讨了道路交通领域中的变化视盲现象。首先,从场景变化特征和驾驶员特征两个方面综述了影响驾驶员变化视盲的影响因素;其次,结合影响因素与变化视盲的特征理论建立了驾驶员变化检测的认知过程模型;最后,在模型的基础上,讨论了提高驾驶员变化检测能力的实际意义和潜在措施,并对未来有关交通安全变化视盲的研究予以展望。     

The role of iconic memory in change-detection tasks

In three experiments, subjects attempted to detect the change of a single item in a visually presented array of items. Subjects' ability to detect a change was greatly reduced if a blank interstimulus interval (ISI) was inserted between the original array and an array in which one item had changed ('change blindness'). However, change detection improved when the location of the change was cued during the blank ISI. This suggests that people represent more information of a scene than change blindness might suggest. We test two possible hypotheses why, in the absence of a cue, this representation fails to produce good change detection. The first claims that the intervening events employed to create change blindness result in multiple neural transients which co-occur with the to-be-detected change. Poor detection rates occur because a serial search of all the transient locations is required to detect the change, during which time the representation of the original scene fades. The second claims that the occurrence of the second frame overwrites the representation of the first frame, unless that information is insulated against overwriting by attention. The results support the second hypothesis. We conclude that people may have a fairly rich visual representation of a scene while the scene is present, but fail to detect changes because they lack the ability to simultaneously represent two complete visual representations.     

The impact of an in-vehicle display on glance distribution in partially automated driving in an on-road experiment

One of the major challenges of designing an HMI for partially automated vehicles is the trade-off between a sufficient level of system information and avoidance of distracting the driver. This study aimed to investigate drivers’ glance behavior as an indicator of distraction when vehicle guidance is partially automated. Therefore, an on-road experiment was conducted comparing two versions of an in-vehicle display (during partially automated driving) and no display (during manual driving) on a heavy congested highway segment. The distribution of drivers’ total glance durations on the HMI showed that visual attention was shifted away from monitoring the central road scene towards looking at the in-vehicle display to a considerable extent. However, an analysis of the distribution of single glance durations supports the view that using partial automation and a respective HMI does not lead to a critical increase in distraction. Driving with a simplified version of the HMI had the potential to reduce glance duration on and thus potential distraction of the in-vehicle display.     

Cell phone-induced failures of visual attention during simulated driving

This research examined the effects of hands-free cell phone conversations on simulated driving. The authors found that these conversations impaired driver's reactions to vehicles braking in front of them. The authors assessed whether this impairment could be attributed to a withdrawal of attention from the visual scene, yielding a form of inattention blindness. Cell phone conversations impaired explicit recognition memory for roadside billboards. Eye-tracking data indicated that this was due to reduced attention to foveal information. This interpretation was bolstered by data showing that cell phone conversations impaired implicit perceptual memory for items presented at fixation. The data suggest that the impairment of driving performance produced by cell phone conversations is mediated, at least in part, by reduced attention to visual inputs.     

Attending to the peripheral world while driving

Do inexperienced drivers see less of the world when driving? Previous research suggests that participants detect fewer peripheral targets while watching video clips of dynamic hazardous driving scenes due to increases in foveal demand (i.e. the presence of a hazard), increases in peripheral target eccentricity, and the lack of driving experience. The current study aimed to further explore the role of experience as a key factor in the potential narrowing of spatial attention, and the possibility of differences in the time course of attentional deployment. It was predicted that the amount of narrowing due to central processing demands would change as a function of driving experience, with more experienced drivers suffering less narrowing due to their mastery of central processing demands in road scenes. The data did not support the narrowing hypothesis, though they did support the alternative strategic difference between the driver groups in the time‐course of attentional deployment. Learners seem to suffer attentional degradation in extra‐foveal regions over a longer period of time whereas experienced drivers seem to invest peripheral attention at the hazard location in short but intense bursts. Copyright © 2002 John Wiley & Sons, Ltd.     

Sleep loss and change detection in driving scenes

Driver sleepiness is a significant road safety problem. Sleep-related crashes occur on both urban and rural roads, yet to date driver-sleepiness research has focused on understanding impairment in rural and motorway driving. The ability to detect changes is an attention and awareness skill vital for everyday safe driving. Previous research has demonstrated that person states, such as age or motivation, influence susceptibility to change blindness (i.e., failure or delay in detecting changes). The current work considers whether sleepiness increases the likelihood of change blindness within urban and rural driving contexts. Twenty fully-licenced drivers completed a change detection ‘flicker’ task twice in a counterbalanced design: once following a normal night of sleep (7–8 h) and once following sleep restriction (5 h). Change detection accuracy and response time were recorded while eye movements were continuously tracked. Accuracy was not significantly affected by sleep loss; however, following sleep loss there was some evidence of slowed change detection responses to urban images, but faster responses for rural images. Visual scanning across the images remained consistent between sleep conditions, resulting in no difference in the probability of fixating on the change target. Overall, the results suggest that sleep loss has minimal impact on change detection accuracy and visual scanning for changes in driving scenes. However, a subtle difference in response time to change detection between urban and rural images indicates that change blindness may have implications for sleep-related crashes in more visually complex urban environments. Further research is needed to confirm this finding.     

Familiarity breeds contempt for the road ahead: The real-world effects of route repetition on visual attention in an expert driver

The majority of journeys by car take place on familiar roads, with many routes being driven time and time again. This familiarity has been linked to mind wandering and reduced attention to specific elements of the visual scene (e.g. speed signs). The current study presents on-road eye tracking data from a driving instructor who drove the same route 28 times, incorporating two types of suburban roads, dual and multi-lane carriageways, and a country road. Data reveal a significant positive correlation between the number of times the same route is navigated and off-road dwell time across all five road sections. In addition, route familiarity was associated with decreasing dwell time on safety-relevant aspects of the road ahead in four out of the five sections. These data suggest that route familiarity can lead to undesirable changes in visual attention on real roads, even for expert drivers under observation.     

Do people with autistic spectrum disorder show normal selection for attention? Evidence from change blindness

People in the general population are typically very poor at detecting changes in pictures of complex scenes. The degree of this ‘change blindness’, however, varies with the content of the scene: when an object is semantically important or contextually inappropriate, people may be more effective at detecting changes. Two experiments investigated change blindness in people with autism, who are known from previous research to be efficient in detecting features yet poor at processing stimuli for meaning and context. The first experiment measured the effect of semantic information while the second investigated the role of context in directing attention. In each task, participants detected the dissimilarity between pairs of images. Both groups showed a main effect of image type in both experimental tasks, showing that their attention was directed to semantically meaningful and contextually inappropriate items. However, the autistic group also showed a greater difficulty detecting changes to semantically marginal items in the first experiment. Conclusions point to a normal selection of items for attention in people with autism spectrum disorders, although this may be combined with difficulty switching or disengaging attention.     

Driving on familiar roads: Automaticity and inattention blindness

This paper describes our research into the processes that govern driver attention and behavior in familiar, well-practiced situations. The experiment examined the effects of extended practice on inattention blindness and detection of changes to the driving environment in a high-fidelity driving simulator. Participants were paid to drive a simulated road regularly over 3 months of testing. A range of measures, including detection task performance and driving performance, were collected over the course of 20 sessions. Performance from a yoked Control Group who experienced the same road scenarios in a single session was also measured. The data showed changes in what drivers reported noticing indicative of inattention blindness, and declining ratings of mental demand suggesting that many participants were “driving without awareness”. Extended practice also resulted in increased sensitivity for detecting changes to road features associated with vehicle guidance and improved performance on an embedded vehicle detection task (detection of a specific vehicle type). The data provide new light on a “tandem model” of driver behavior that includes both explicit and implicit processes involved in driving performance. The findings also suggest reasons drivers are most likely to crash at locations very near their homes.     

Failures to see: attentive blank stares revealed by change blindness

Change blindness illustrates a remarkable limitation in visual processing by demonstrating that substantial changes in a visual scene can go undetected. Because these changes can ultimately be detected using top-down driven search processes, many theories assign a central role to spatial attention in overcoming change blindness. Surprisingly, it has been reported that change blindness can occur during blink-contingent changes even when observers fixate the changing location [O'Regan, J. K., Deubel, H., Clark, J. J., & Rensink, R. A. (2000). Picture changes during blinks: Looking without seeing and seeing without looking. Visual Cognition, 7, 191-212]. However, eye blinks produce a transient disruption of vision that is independent of any associated changes in the retinal image. We determined whether these 'attentive blank stares' could occur in the absence of blink-mediated visual suppression. Using a flicker change-blindness paradigm we confirm that despite direct attentive fixations, obvious scene changes often remain undetected. We conclude that change detection involves object or feature based attentional mechanisms, which can be 'misdirected' despite the allocation of spatial attention to the position of the change.     

驾驶员选择性注意过程中的规则图式启动效应

本研究将驾驶无意视盲范式与交通违规事件识别任务相结合, 通过两个实验分别探究任务性质(有提示、无提示)和规则图式训练(训练、未训练)对驾驶员识别交通信号和违规事件的影响。结果发现, 交通规则提示能够提高有经验的驾驶员识别交通信号的正确率(实验1); 对于新手驾驶员, 则需要结合规则图式训练才能起到相同效果(实验2)。研究表明驾驶员选择性注意过程中存在规则图式启动效应, 图式训练能够弥补新手驾驶员经验的不足。     

The scene and the unseen: Manipulating photographs for experiments on change blindness and scene memory

The change blindness paradigm, in which participants often fail to notice substantial changes in a scene, is a popular tool for studying scene perception, visual memory, and the link between awareness and attention. Some of the most striking and popular examples of change blindness have been demonstrated with digital photographs of natural scenes; in most studies, however, much simpler displays, such as abstract stimuli or “free-floating” objects, are typically used. Although simple displays have undeniable advantages, natural scenes remain a very useful and attractive stimulus for change blindness research. To assist researchers interested in using natural-scene stimuli in change blindness experiments, we provide here a step-by-step tutorial on how to produce changes in natural-scene images with a freely available image-processing tool (GIMP). We explain how changes in a scene can be made by deleting objects or relocating them within the scene or by changing the color of an object, in just a few simple steps. We also explain how the physical properties of such changes can be analyzed using GIMP and MATLAB (a high-level scientific programming tool). Finally, we present an experiment confirming that scenes manipulated according to our guidelines are effective in inducing change blindness and demonstrating the relationship between change blindness and the physical properties of the change and inter-individual differences in performance measures. We expect that this tutorial will be useful for researchers interested in studying the mechanisms of change blindness, attention, or visual memory using natural scenes.     

Efficient summary statistical representation when change localization fails

People are sensitive to the summary statistics of the visual world (e.g., average orientation/speed/facial expression). We readily derive this information from complex scenes, often without explicit awareness. Given the fundamental and ubiquitous nature of summary statistical representation, we tested whether this kind of information is subject to the attentional constraints imposed by change blindness. We show that information regarding the summary statistics of a scene is available despite limited conscious access. In a novel experiment, we found that while observers can suffer from change blindness (i.e., not localize where change occurred between two views of the same scene), observers could nevertheless accurately report changes in the summary statistics (or “gist”) about the very same scene. In the experiment, observers saw two successively presented sets of 16 faces that varied in expression. Four of the faces in the first set changed from one emotional extreme (e.g., happy) to another (e.g., sad) in the second set. Observers performed poorly when asked to locate any of the faces that changed (change blindness). However, when asked about the ensemble (which set was happier, on average), observer performance remained high. Observers were sensitive to the average expression even when they failed to localize any specific object change. That is, even when observers could not locate the very faces driving the change in average expression between the two sets, they nonetheless derived a precise ensemble representation. Thus, the visual system may be optimized to process summary statistics in an efficient manner, allowing it to operate despite minimal conscious access to the information presented.     

How Stimulus Variables Combine to Affect Change Blindness

Change blindness is the inability to detect changes that occur in a scene, when the scene is briefly obscured while the change happens. It has been found to occur during driving simulations and computer use for example. Scene-Complexity, stimulus On-Time and time for which a scene is obscured can all affect our ability to detect changes (or change blindness). In most studies parameters have been selected to induce change blindness with little consideration of the extent to which change blindness might be induced. There is however evidence that variables that describe the visual scene can affect likelihood of detecting changes (Rensink Visual Cognition 7:345?C376, 2000). These effects have in this paper been explored in combination. Increasing Scene-Complexity, decreasing stimulus On-Time and increasing the duration for which a scene is obscured all increase change blindness but they all interact to further increase the likelihood of changes being missed. In order to reduce change blindness in a changing scene, all the variables need to be considered.