This research examined whether or not an auditory stimulus would affect rates of change blindness. Change blindness occurs when there is a failure to detect an obvious change to a visual scene. For this experiment 40 participants were asked to determine if a change occurred between two pictures. This involved an original picture shown for 1 second, a neutral screen shown for 50 milliseconds and then either a modified version of the original image or the same image for 1 second and then repeated. Participants then determined whether a change occurred in the visual display. For some participants a familiar song played on repeat during the visual task. My goal was to determine if music would affect rates of change blindness and how quickly changes would be detected if present. I found that participants in both the music and non-music conditions were more accurate when there was no change to a scene. Participants in the music condition also took longer to respond as opposed to the control group. When examining reaction times of only correct responses, both conditions responded in a similar amount of time for pictures with changes. In trials with no changes the participants in the music condition took longer to respond than the control group. Overall, it appears that music had a negative effect on reaction times when a change was present. Participants were also more accurate in detecting pictures with no changes as opposed to pictures with changes.

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In this study, participants performed a change detection task. Specifically we examined whether participants had to fixate on a difference between two images before they could detect it. Thirty-six participants performed a change detection task in either a 3 minute or a 1.5 minute condition. We found a significant interaction between task duration and fixation type (whether the participant had fixated on the difference in both, one, or neither image). Participants found a greater number of differences given more time only when they fixated on the difference in both images. The number of differences which were detected by participants with a fixation on only one image or on neither image did not increase with a corresponding increase in time, indicating that some mechanical error may be involved. This suggests that participants need to fixate on a difference before being able to detect it.

A common problem in vision research is explaining how humans perceive a coherent, detailed and stable world despite the fact that the eyes make constant, jumpy movements and the fact that only a small part of the visual field can be resolved in detail at any one time. This is essentially a problem of integration over time - how successive views of the visual world can be used to create the impression of a continuous and stable environment. A common way of studying this problem is to use complete visual scenes as stimuli and present a changed scene after a disruption such as an eye movement or a blank screen. It is found in these studies that observers have great difficulty detecting changes made during a disruption, even though these changes are immediately and easily detectable when the disruption is removed. These results have highlighted the importance of motion cues in tracking changes to the environment, but also reveal the limited nature of the internal representation. Change blindness studies are interesting as demonstrations but can be difficult to interpret as they are usually applied to complex, naturalistic scenes. More traditional studies of scene analysis, such as visual search, are more abstract in their formulation, but offer more controlled stimulus conditions. In a typical visual search task, observers are presented with an array of objects against a uniform background and are required to report on the presence or absence of a target object that is differentiable from the other objects in some way. More recently, scene analysis has been investigated by combining change blindness and visual search in the `visual search for change' paradigm, in which observers must search for a target object defined by a change over two presentations of the set of objects. The experiments of this thesis investigate change blindness using the visual search for change paradigm, but also use principles of design from psychophysical experiments, dealing with detection and discrimination of basic visual qualities such as colour, speed, size, orientation and spatial frequency. This allows the experiments to precisely examine the role of these different features in the change blindness process. More specifically, the experiments are designed to look at the capacity of visual short-term memory for different visual features, by examining the retention of this information across the temporal gaps in the change blindness experiments. The nature and fidelity of representations in visual short-term memory is also investigated by manipulating (i) the manner in which featural information is distributed across space and objects, (ii) the time for which the information is available, (iii) the manner in which observers must respond to that information. Results point to a model in which humans analyse objects in a scene at the level of features/attributes rather than at a pictorial/object level. Results also point to the fact that the working representations which humans retain during visual exploration are similarly feature- rather than object-based. In conclusion the thesis proposes a model of scene analysis in which attention and vSTM capacity limits are used to explain the results from a more information theoretic standpoint.

Introduction: Medical errors are major hazards, and lapses in non-technical skills such as situational awareness contribute to most incidents. Risks are concentrated in acute care, and in crisis situations clinicians can apparently ignore vital information. Poor workplace ergonomics contributes to risk. Existing work into perceptual errors offers insights, but these phenomena have been little researched in medicine. This thesis considers medical non-technical skills and how they are taught, and explores vulnerability to inattentional and change blindness. Methods: Medical human factors and the psychology of perceptual error were reviewed, and a mixed-methods assessment of postgraduate medical curricula completed. Experiments assessed clinicians' interaction with clinical monitoring devices using eye-tracking, and studies were conducted exposing clinicians to various perceptual error stimuli using non-clinical and clinical videos, and simulation. A survey was also conducted to assess clinicians' insight into the phenomena of perceptual error. Results: Non-technical skills feature poorly in medical curricula, and equipment is poorly standardised in critical care areas. Unfamiliar devices slow response times and increase error rate. Clinical training confers no generalisable advantage in perceptual reliability. Even expert clinicians miss important events. Two out of every three life-support instructors for example missed a critical failure in the patient's oxygen supply when watching a recorded emergency simulation. The insight and understanding healthcare staff have of perceptual errors is poor, leading to significant overestimates of perceptual reliability that could have consequences for clinical practice. Conclusions: Perceptual errors represent a latent risk factor contributing to loss of situational awareness. High rates of perceptual error were observed in the video-based experiment. Although lower rates were observed in simulation, important events were still missed by participants that could have serious consequences. The incidence of perceptual error appears sensitive to the method used to test for it, and this has important implications for the design of future experiments testing for these phenomena. Mitigating perceptual error is likely to be challenging, but relatively simple adjustments to team practices in emergency situations may be fruitful.

Research has shown that people often fail to notice changes to visual scenes. This phenomenon is known as change blindness. This study investigated the effect of facial feature transformations on change blindness using change detection tasks involving a person as the object of change. 301 participants viewed a photo-story comprised of a few still frames. In the final frame, a selected facial feature of a character in the story was altered. Four different photo-stories were used, each utilising a different alteration. Questionnaires designed to determine whether the change was detected were administered. Results showed that changes to facial features considered to be more salient produced higher levels of change detection. A flicker test using the same images from the photo-story was administered to a further 75 participants and showed a similar pattern of results. It was concluded that in order to detect change, the changing stimuli have to be both salient and meaningful.

本研究欲了解「大家來找碴」（Spot the Differences）此類偵測作業的遊戲在設計時應注意的元素為何？兩個實驗皆為參與者內設計，在實驗一中操弄產品置入在遊戲畫面中的聚焦區（area of interest, AOI）與否，以及產品是否為遊戲目標，測量偵測的正確率、反應時間和再認表現，以檢視產品置入在遊戲中是否能吸引注意力？結果發現當產品置入在聚焦區時的反應時間快於在非聚焦區。當產品是遊戲目標時的再認表現，優於不是遊戲目標時；而當產品位在非聚焦區時的再認表現，會優於廣告在聚焦區時。然而，實驗一中的產品並未包含商標，為進一步探討探討廣告效益，在實驗二中加入有商標的廣告商品，並使用眼動儀，測量參與者對商品的眼動處理模式，如凝視時間（fixation duration）與凝視次數（number of fixation），並請參與者評估對商品的喜好程度和購買意圖。結果發現商品置入在聚焦區的反應時間顯著快於非聚焦區，但商品置入在非聚焦區時的再認表現、喜好程度和購買意圖皆優於置入在聚焦區時。眼動的結果發現，商品是遊戲目標時和在聚焦區時有更長的凝視時間和更多的凝視次數。依據實驗一與實驗二的結果顯示，參與者有可能是在無意識受到商品曝光的影響而產生廣告效果，建議未來研究可加入內隱指標探討當商品位在非聚焦區時的廣告效果，以提供更直接的證據驗證。 / The purpose of this study is to investigate what elements that we should notice when we design kind of Spot-the-Differences games. Two within-subject-designed experiments were conducted. In experiment 1, we manipulated the location of products（area-of-interest or non-area-of-interest）and the type of products（target or non-target）to examine how products attract our attention in in-game advertising.. The results of experiment 1 showed that when products were in the AOI, the reaction times were shorter than those in non-AOI. However, participants could recognize the products better when they were in non-AOI. Furthermore, participants could recognize the products better when products were the targets than non-targets in the game. In order to investigate the effect of in-game advertising, in experiment 2, we added trade mark and used an eye tracker to examine the role of visual attention in-game advertising. Besides, we used liking and purchase intention as an index of advertising effects. The results of experiment 2 showed that products that were in the AOI attracted participants' attention more quickly. However, products in non-AOI showed better recognition performance, liking and purchase intention than those in AOI. The results of eye movements showed that longer fixation duration and more fixation number was observed for targets than for non-targets. According to the results, the effects of advertisement may be resulted from participants being exposed for products in an unconscious manner. Future studies could add the index of unconscious processing to clarify the implicit effects of in-game advertising.

Variable speed limits (VSL) are used more commonly around the globe lately. Although on a macroscopic level positive effects of VSLs have been reported, the caveat is that the impact of VSLs is very sensitive to the level of driver compliance. Thus far it is unknown whether all individual drivers are actually able to notice when a speed limit changes into another speed limit; a prerequisite for purposeful speed limit compliance in the first place. To simulate regular driving conditions, twenty-four participants were familiarised with a particular route by driving the same route in a driving simulator nineteen times on five separate days. Part of the route consisted of a motorway where VSL signs were regularly displayed above every driving lane. At drive nineteen, speed limits changed from 80 km/h to 100 km/h on four out of eight consecutive signs. After passing all signs, one expects 6.25% of the participants still to be unaware that the speed limit had increased (based on chance), while the results showed most participants had failed to notice the speed limit change (58.3%). Instead, they saw what they expected to see: a speed limit of 80 km/h. If the speed change had been vice versa, in other words from 100 km/h to 80 km/h, this would immediately result in speed offences, though not deliberately at all.

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