Change Blindness and Its Determinants

Mgr. Michaela Porubanová

Doctoral thesis

Abstract:

Every moment, we perceive visual information in the environment, and regardless of the complexity of the information, we have a very powerful impression that the world is there, at our disposal, and the way we visually represent it is veridical to its actual image. However, the discovery of the phenomenon of change blindness, or an extreme difficulty in detecting changes in a visual field when a disruption in visual continuity occurs, has undermined the notion that visual representations are intricate, and suggests that memory for visual scenes might be very poor (O’Regan, 1992; O’Regan & Noë, 2001; Rensink, 2000). Change blindness has since become one of the most well-known and well-studied phenomenon in the study of visual attention and visual working memory, and has provided powerful methods to study visual attention in general. This dissertation can be split into two different parts. The first part deals with understanding the role of high-level factors in scene perception using the change blindness (flicker) paradigm. The second part focuses on the role of the emotional context of scenes and personality traits on change blindness performance. In the first study, we were interested in understanding whether there are high-level scene factors that influence change detection. Our experiment was motivated by several facts. Firstly, scene perception research shows that the human visual system has a tendency to attend predominantly to informative and important parts of a scene (Buswell, 1935; Henderson, 2003; Loftus & Mackworth, 1978; Yarbus, 1967), and that in active tasks such as change detection, attending to information with high visual saliency (i.e. spatial frequency, color, and intensity) is inhibited (Henderson, 2003; Henderson & Hollingworth, 2003; Turano, Geruschat, & Baker, 2003). Therefore attention is rather dependent on high-level factors (Beck et al., 2004; Hollingsworth & Henderson, 2000; Rensink et al., 1997). Taken together, the goal of the first part of the dissertation was to explore what high-level scene information is considered by the human visual system informative and important. In the experiment, observers inspected various sets of two real-world scene images which featured a changed aspect. The images were shown alternating in sequential order (i.e., the flicker task) and the observers were asked to click on the location where the change had occurred. The results demonstrated that not all changes present in a scene have the same likelihood to be detected. The changes that seem to be dominant in attracting attention were found to be changes occurring in the central region, context-related changes, probable changes, and changes occurring within a figure. Our results are consistent with results of other studies. For instance, research on scene perception has shown that changes in the central region are detected faster than those in the marginal (Rensink et al., 1997), changes inconsistent with the scene context are detected faster than those consistent with the scene context (Hollingsworth & Henderson, 2000), probable changes faster than improbable ones (Beck et al., 2004), changes in a figure are detected to a greater extent than ones in the background (Mazza et al., 2005; Turatto et al., 2002). Interestingly, the detection of changes occurring within close proximity to a figure was most difficult. This indicates that when searching for changes in scenes, parts of the scenes close to the most powerful attractors are being shadowed, and therefore seem to be ignored by selective attention. This could be ascribed to the role of expectations in change detection tasks. Therefore, we believe that specifically in explicit change detection tasks, an individual might use a certain heuristic that helps her scan the scene. The study discusses the significance of the categories under which a stimulus falls in terms of its non-visual or semantic properties. The goal of the second study fo

Abstract:

cused specifically on three areas of the effect of emotion on attention: 1. the role of emotional context in change detection; 2. the role of emotional states in change detection; and 3. the role of time-invariant personality traits in change detection. In the study, standardized and validated images from IAPS (International Affective Picture System, Lang, Bradley, & Cuthbert, 2005) were used in order to examine the role of emotional context (created by real-world scenes with various degrees of valence and arousal) on the ability to detect changes within those images. It was believed that change detection would be affected by the emotional significance of the scenes via two mechanisms. The first mechanism is the modification of attentional scope (FOV), which would be greater for positive than negative images, allowing more relevant information to be processed simultaneously and resulting in faster change detection performance. For instance, research found a correlation between FOV and reaction time in an intentional change detection tasks (such as flicker) (Pringle, Irwin, Kramer, & Atchley 2001). We found the greatest accuracy of change detection for changes occurring in positive and negative scenes (compared with neutral scenes). Secondly and most importantly, changes in negative scenes (and also positive scenes, though not with statistical significance) were detected faster than changes in neutral scenes. The results show that emotional significance of a scene does have an effect on spatial attention. Quick and successful change detection in flicker tasks requires spatial attention to be widened and maintenance of the information selected by attention from the particular scene area. Much research has provided evidence for the prioritized processing of emotional stimuli. Additionally, it is clear from our study that the emotional significance of visual scenes has a differential effect on attention. Similarly, Anderson & Phelps (2001) showed that attentional blink for the second target identification is alleviated when the second target represents an emotionally significant stimulus (in that case, an emotional word). Most et al. (2005), using the RSVP paradigm (rapid serial visual presentation), demonstrated that presenting an emotional stimulus prior to the onset of a target hinders target detection. Clearly, emotional stimuli not only enjoy prioritized processing but utilize attention resources and create interference when tasks require a brief presentation of neutral stimuli. Secondly, we looked at the role of individuals’ affective states in change blindness. Many studies suggest that positive emotional states, when compared with neutral or negative states, increase the field of view and reduce attentional biases in iconic memory tasks (Kuhnbandner et al., 2011), flanker tasks (Rowe et al., 2007), or Navon’s global-local processing task (Gasper & Clore, 2002). In the current study, however, no experimental manipulation of emotional states took place; rather each participant assessed her own emotional state prior to the beginning of change detection task. Based on the results, overall emotional states did not correlate with the change detection latency performance to a great extent. Only ‘feeling nervous’ positively correlated with the overall change detection performance. ‘Feeling alert’ negatively correlated with change detection performance, but only for neutral images. The results support the hypothesis that negative emotions (in our case nervousness) impaired performance in attentional task. Secondly, positive emotions, such as feeling alert, improved reaction times. In the part concerning the role of time-invariant personality traits in change detection, we used Cloninger’s Temperament and Character Inventory to assess participants’ personality traits. The relationship between Harm Avoidance, a temperament dimension that refers to sensitivity toward aversive stimuli and can be perceived as one’s trait anxiety, in relation to the performance in attentional task was especially of interest to the current study. The results show that Harm Avoidance in particular is associated with responses to emotional stimuli processing. The association is, interestingly, to positive, neutral, as well as with the overall change detection performance, but not with negative stimuli processing. Interestingly, Empathy has been negatively correlated with the performance in all emotion categories, indicating that greater scores in Empathy lead to shorter detection times. The overall results indicate that visual attention and its allocation is navigated via different external (high-level scene factors, or emotional information), or internal (emotional states, or personality traits) factors, and the reason of their role in influencing visual attention are discussed in the dissertation.

Abstract:

Every moment, we perceive visual information in the environment, and regardless of the complexity of the information, we have a very powerful impression that the world is there, at our disposal, and the way we visually represent it is veridical to its actual image. However, the discovery of the phenomenon of change blindness, or an extreme difficulty in detecting changes in a visual field when a disruption in visual continuity occurs, has undermined the notion that visual representations are intricate, and suggests that memory for visual scenes might be very poor (O’Regan, 1992; O’Regan & Noë, 2001; Rensink, 2000). Change blindness has since become one of the most well-known and well-studied phenomenon in the study of visual attention and visual working memory, and has provided powerful methods to study visual attention in general. This dissertation can be split into two different parts. The first part deals with understanding the role of high-level factors in scene perception using the change blindness (flicker) paradigm. The second part focuses on the role of the emotional context of scenes and personality traits on change blindness performance. In the first study, we were interested in understanding whether there are high-level scene factors that influence change detection. Our experiment was motivated by several facts. Firstly, scene perception research shows that the human visual system has a tendency to attend predominantly to informative and important parts of a scene (Buswell, 1935; Henderson, 2003; Loftus & Mackworth, 1978; Yarbus, 1967), and that in active tasks such as change detection, attending to information with high visual saliency (i.e. spatial frequency, color, and intensity) is inhibited (Henderson, 2003; Henderson & Hollingworth, 2003; Turano, Geruschat, & Baker, 2003). Therefore attention is rather dependent on high-level factors (Beck et al., 2004; Hollingsworth & Henderson, 2000; Rensink et al., 1997). Taken together, the goal of the first part of the dissertation was to explore what high-level scene information is considered by the human visual system informative and important. In the experiment, observers inspected various sets of two real-world scene images which featured a changed aspect. The images were shown alternating in sequential order (i.e., the flicker task) and the observers were asked to click on the location where the change had occurred. The results demonstrated that not all changes present in a scene have the same likelihood to be detected. The changes that seem to be dominant in attracting attention were found to be changes occurring in the central region, context-related changes, probable changes, and changes occurring within a figure. Our results are consistent with results of other studies. For instance, research on scene perception has shown that changes in the central region are detected faster than those in the marginal (Rensink et al., 1997), changes inconsistent with the scene context are detected faster than those consistent with the scene context (Hollingsworth & Henderson, 2000), probable changes faster than improbable ones (Beck et al., 2004), changes in a figure are detected to a greater extent than ones in the background (Mazza et al., 2005; Turatto et al., 2002). Interestingly, the detection of changes occurring within close proximity to a figure was most difficult. This indicates that when searching for changes in scenes, parts of the scenes close to the most powerful attractors are being shadowed, and therefore seem to be ignored by selective attention. This could be ascribed to the role of expectations in change detection tasks. Therefore, we believe that specifically in explicit change detection tasks, an individual might use a certain heuristic that helps her scan the scene. The study discusses the significance of the categories under which a stimulus falls in terms of its non-visual or semantic properties. The goal of the second study fo

Abstract:

cused specifically on three areas of the effect of emotion on attention: 1. the role of emotional context in change detection; 2. the role of emotional states in change detection; and 3. the role of time-invariant personality traits in change detection. In the study, standardized and validated images from IAPS (International Affective Picture System, Lang, Bradley, & Cuthbert, 2005) were used in order to examine the role of emotional context (created by real-world scenes with various degrees of valence and arousal) on the ability to detect changes within those images. It was believed that change detection would be affected by the emotional significance of the scenes via two mechanisms. The first mechanism is the modification of attentional scope (FOV), which would be greater for positive than negative images, allowing more relevant information to be processed simultaneously and resulting in faster change detection performance. For instance, research found a correlation between FOV and reaction time in an intentional change detection tasks (such as flicker) (Pringle, Irwin, Kramer, & Atchley 2001). We found the greatest accuracy of change detection for changes occurring in positive and negative scenes (compared with neutral scenes). Secondly and most importantly, changes in negative scenes (and also positive scenes, though not with statistical significance) were detected faster than changes in neutral scenes. The results show that emotional significance of a scene does have an effect on spatial attention. Quick and successful change detection in flicker tasks requires spatial attention to be widened and maintenance of the information selected by attention from the particular scene area. Much research has provided evidence for the prioritized processing of emotional stimuli. Additionally, it is clear from our study that the emotional significance of visual scenes has a differential effect on attention. Similarly, Anderson & Phelps (2001) showed that attentional blink for the second target identification is alleviated when the second target represents an emotionally significant stimulus (in that case, an emotional word). Most et al. (2005), using the RSVP paradigm (rapid serial visual presentation), demonstrated that presenting an emotional stimulus prior to the onset of a target hinders target detection. Clearly, emotional stimuli not only enjoy prioritized processing but utilize attention resources and create interference when tasks require a brief presentation of neutral stimuli. Secondly, we looked at the role of individuals’ affective states in change blindness. Many studies suggest that positive emotional states, when compared with neutral or negative states, increase the field of view and reduce attentional biases in iconic memory tasks (Kuhnbandner et al., 2011), flanker tasks (Rowe et al., 2007), or Navon’s global-local processing task (Gasper & Clore, 2002). In the current study, however, no experimental manipulation of emotional states took place; rather each participant assessed her own emotional state prior to the beginning of change detection task. Based on the results, overall emotional states did not correlate with the change detection latency performance to a great extent. Only ‘feeling nervous’ positively correlated with the overall change detection performance. ‘Feeling alert’ negatively correlated with change detection performance, but only for neutral images. The results support the hypothesis that negative emotions (in our case nervousness) impaired performance in attentional task. Secondly, positive emotions, such as feeling alert, improved reaction times. In the part concerning the role of time-invariant personality traits in change detection, we used Cloninger’s Temperament and Character Inventory to assess participants’ personality traits. The relationship between Harm Avoidance, a temperament dimension that refers to sensitivity toward aversive stimuli and can be perceived as one’s trait anxiety, in relation to the performance in attentional task was especially of interest to the current study. The results show that Harm Avoidance in particular is associated with responses to emotional stimuli processing. The association is, interestingly, to positive, neutral, as well as with the overall change detection performance, but not with negative stimuli processing. Interestingly, Empathy has been negatively correlated with the performance in all emotion categories, indicating that greater scores in Empathy lead to shorter detection times. The overall results indicate that visual attention and its allocation is navigated via different external (high-level scene factors, or emotional information), or internal (emotional states, or personality traits) factors, and the reason of their role in influencing visual attention are discussed in the dissertation.

Keywords

change blindness, high-level factors, personality, emotion, IAPS, flicker paradigm, visual attention

Language used: English

Date on which the thesis was submitted / produced: 15. 7. 2013

Thesis defence

• Date of defence: 7. 8. 2013
• Supervisor: Mgr. Radovan Šikl, Ph.D.
• Reader: prof. PhDr. Tomáš Urbánek, Ph.D., doc. PhDr. Ján Rybár, PhD.

Masaryk University

Faculty of Social Studies

Doctoral programme / field:
Psychology (4-years) / General Psychology