Not quite so blind: Semantic processing despite inattentional blindness

Deep learning from atrioventricular plane displacement in patients with Takotsubo syndrome: lighting up the black-box

Aims

The spatiotemporal deep convolutional neural network (DCNN) helps reduce echocardiographic readers' erroneous 'judgement calls' on Takotsubo syndrome (TTS). The aim of this study was to improve the interpretability of the spatiotemporal DCNN to discover latent imaging features associated with causative TTS pathophysiology.

Methods and results

We applied gradient-weighted class activation mapping analysis to visualize an established spatiotemporal DCNN based on the echocardiographic videos to differentiate TTS (150 patients) from anterior wall ST-segment elevation myocardial infarction (STEMI, 150 patients). Forty-eight human expert readers interpreted the same echocardiographic videos and prioritized the regions of interest on myocardium for the differentiation. Based on visualization results, we completed optical flow measurement, myocardial strain, and Doppler/tissue Doppler echocardiography studies to investigate regional myocardial temporal dynamics and diastology. While human readers' visualization predominantly focused on the apex of the heart in TTS patients, the DCNN temporal arm's saliency visualization was attentive on the base of the heart, particularly at the atrioventricular (AV) plane. Compared with STEMI patients, TTS patients consistently showed weaker peak longitudinal displacement (in pixels) in the basal inferoseptal (systolic: 2.15 ± 1.41 vs. 3.10 ± 1.66, P < 0.001; diastolic: 2.36 ± 1.71 vs. 2.97 ± 1.69, P = 0.004) and basal anterolateral (systolic: 2.70 ± 1.96 vs. 3.44 ± 2.13, P = 0.003; diastolic: 2.73 ± 1.70 vs. 3.45 ± 2.20, P = 0.002) segments, and worse longitudinal myocardial strain in the basal inferoseptal (-8.5 ± 3.8% vs. -9.9 ± 4.1%, P = 0.013) and basal anterolateral (-8.6 ± 4.2% vs. -10.4 ± 4.1%, P = 0.006) segments. Meanwhile, TTS patients showed worse diastolic mechanics than STEMI patients (E'/septal: 5.1 ± 1.2 cm/s vs. 6.3 ± 1.5 cm/s, P < 0.001; S'/septal: 5.8 ± 1.3 cm/s vs. 6.8 ± 1.4 cm/s, P < 0.001; E'/lateral: 6.0 ± 1.4 cm/s vs. 7.9 ± 1.6 cm/s, P < 0.001; S'/lateral: 6.3 ± 1.4 cm/s vs. 7.3 ± 1.5 cm/s, P < 0.001; E/E': 15.5 ± 5.6 vs. 12.5 ± 3.5, P < 0.001).

Conclusion

The spatiotemporal DCNN saliency visualization helps identify the pattern of myocardial temporal dynamics and navigates the quantification of regional myocardial mechanics. Reduced AV plane displacement in TTS patients likely correlates with impaired diastolic mechanics.

Preserved sensory processing but hampered conflict detection when stimulus input is task-irrelevant

Conflict detection in sensory input is central to adaptive human behavior. Perhaps unsurprisingly, past research has shown that conflict may even be detected in the absence of conflict awareness, suggesting that conflict detection is an automatic process that does not require attention. To test the possibility of conflict processing in the absence of attention, we manipulated task relevance and response overlap of potentially conflicting stimulus features across six behavioral tasks. Multivariate analyses on human electroencephalographic data revealed neural signatures of conflict only when at least one feature of a conflicting stimulus was attended, regardless of whether that feature was part of the conflict, or overlaps with the response. In contrast, neural signatures of basic sensory processes were present even when a stimulus was completely unattended. These data reveal an attentional bottleneck at the level of objects, suggesting that object-based attention is a prerequisite for cognitive control operations involved in conflict detection.

Focusing your attention on one thing can leave you surprisingly unaware of what goes on around you. A classic experiment known as ‘the invisible gorilla’ highlights this phenomenon. Volunteers were asked to watch a clip featuring basketball players, and count how often those wearing white shirts passed the ball: around half of participants failed to spot that someone wearing a gorilla costume wandered into the game and spent nine seconds on screen.

Yet, things that you are not focusing on can sometimes grab your attention anyway. Take for example, the ‘cocktail party effect’, the ability to hear your name among the murmur of a crowded room. So why can we react to our own names, but fail to spot the gorilla? To help answer this question, Nuiten et al. examined how paying attention affects the way the brain processes input.

Healthy volunteers were asked to perform various tasks while the words ‘left’ or ‘right’ played through speakers. The content of the word was sometimes consistent with its location (‘left’ being played on the left speaker), and sometimes opposite (‘left’ being played on the right speaker). Processing either the content or the location of the word is relatively simple for the brain; however detecting a discrepancy between these two properties is challenging, requiring the information to be processed in a brain region that monitors conflict in sensory input.

To manipulate whether the volunteers needed to pay attention to the words, Nuiten et al. made their content or location either relevant or irrelevant for a task. By analyzing brain activity and task performance, they were able to study the effects of attention on how the word properties were processed.

The results showed that the volunteers’ brains were capable of dealing with basic information, such as location or content, even when their attention was directed elsewhere. But discrepancies between content and location could only be detected when the volunteers were focusing on the words, or when their content or location was directly relevant to the task.

The findings by Nuiten et al. suggest that while performing a difficult task, our brains continue to react to basic input but often fail to process more complex information. This, in turn, has implications for a range of human activities such as driving. New technology could potentially help to counteract this phenomenon, aiming to direct attention towards complex information that might otherwise be missed.

Implicit processing during inattentional blindness: A systematic review and meta-analysis

The occurrence of implicit processing of visual stimuli during inattentional blindness is still a matter of debate. To assess the evidence available in this debate, we conducted a systematic review of articles that explored whether unexpected visual stimuli presented during inattentional blindness are implicitly processed despite not being reported. Additionally, we employed meta-analysis to combine 59 behavioral experiments and investigate the statistical support for such implicit processing across experiments. Results showed that visual stimuli can be processed when unattended and unnoticed. Additionally, we reviewed the measures used to assess participants' awareness of the unexpected stimuli. We also employed meta-analysis to search for differences in awareness of the unexpected stimuli that may result from adopting distinct criteria to categorize participants as aware or unaware. The results showed that the overall effect of awareness changed depending on whether more demanding or less demanding measures of awareness were employed. This suggests that the choice of awareness measure may influence conclusions about whether processing of the US is implicit or explicit. We discuss the implications of these results for the study of implicit processing and the role of attention in visual cognition.

Loads of unconscious processing: The role of perceptual load in processing unattended stimuli during inattentional blindness

Inattentional blindness describes the failure to detect an unexpected but clearly visible object when our attention is engaged elsewhere. While the factors that determine the occurrence of inattentional blindness are already well understood, there is still a lot to learn about whether and how we process unexpected objects that go unnoticed. Only recently it was shown that although not consciously aware, characteristics of these stimuli can interfere with a primary task: Classification of to-be-attended stimuli was slower when the content of the task-irrelevant, undetected stimulus contradicted that of the attended, to-be-judged stimuli. According to Lavie’s perceptual load model, irrelevant stimuli are likely to reach awareness under conditions of low perceptual load, while they remain undetected under high load, as attentional resources are restricted to the content of focused attention. In the present study, we investigated the applicability of Lavie’s predictions for the processing of stimuli that remain unconscious due to inattentional blindness. In two experiments, we replicated that unconsciously processed stimuli can interfere with intended responses. Also, our manipulation of perceptual load did have an effect on primary task performance. However, against our hypothesis, these effects did not interact with each other. Thus, our results suggest that high perceptual load cannot prevent task-irrelevant stimuli that remain undetected from being processed to an extent that enables them to affect performance in a primary task.

Guessing right: Preconscious processing in inattentional blindness

Much research has been conducted on the determinants of inattentional blindness-the failure to miss an unexpected but salient stimulus in plain view. Far less research has been concerned with the fate of those objects that go unnoticed in such a setting. The available evidence suggests that objects that are not consciously noticed due to inattentional blindness are still processed to a certain degree. The present study substantiated and generalised this limited evidence by reanalysing 16 datasets in regard to participants' guessing accuracy in multiple-choice questions concerning the unexpected object: Participants who did not notice the critical object showed guessing accuracy that lay significantly above chance. Thus, stimuli that are not consciously noticed (i.e., cannot be reported) can nevertheless exert an influence on seemingly random choices. Modality of the primary task as well as performance in the primary task and in a divided-attention trial were evaluated as potential moderators. Methodological limitations such as the design and implementation of the multiple-choice questions and the generalisability of our findings are discussed, and promises of the present approach for future studies are presented.

Ich sehe was, was du nicht siehst

Zusammenfassung. Wenn wir unsere Aufmerksamkeit einer Aufgabe zuwenden, nehmen wir Dinge, die währenddessen unerwartet auftauchen, häufig nicht bewusst wahr – obwohl sie unmittelbar in unserem Blickfeld erscheinen. Dieses Phänomen, das als Inattentional Blindness bezeichnet wird, kann fatale Konsequenzen in alltäglichen Situationen und auch einen ernstzunehmenden Einfluss auf sportliche Leistungen haben. In Ergänzung zu vorheriger Forschung zeigen meine eigenen Ergebnisse, dass eine Vielzahl situativer Faktoren die Wahrscheinlichkeit, mit der Inattentional Blindness auftritt, beeinflussen können. Dazu zählen unter anderem bestimmte Eigenschaften des unerwarteten Objekts sowie Kontextfaktoren. Im Gegensatz dazu scheinen interindividuelle Unterschiede über die situativen Einflüsse hinaus kaum (oder zumindest nicht reliabel) vorherzusagen, ob Inattentional Blindness auftritt oder nicht. Während es also eine feste Wahrscheinlichkeit über alle Personen hinweg gibt, dass ein unerwartetes Objekt bemerkt wird (deterministischer Aspekt), kann anhand der Persönlichkeitsstruktur und der kognitiven Fähigkeiten dieser Personen nicht vorhergesagt werden, wer von ihnen das unerwartete Objekt entdecken wird und wer nicht (stochastischer Aspekt).