Pupil Dilation Dynamics Track Attention to High-Level Information

It has long been thought that the eyes index the inner workings of the mind. Consistent with this intuition, empirical research has demonstrated that pupils dilate as a consequence of attentional effort. Recently, Smallwood et al. (2011) demonstrated that pupil dilations not only provide an index of overall attentional effort, but are time-locked to stimulus changes during attention (but not during mind-wandering). This finding suggests that pupil dilations afford a dynamic readout of conscious information processing. However, because stimulus onsets in their study involved shifts in luminance as well as information, they could not determine whether this coupling of stimulus and pupillary dynamics reflected attention to low-level (luminance) or high-level (information) changes. Here, we replicated the methodology and findings of Smallwood et al. (2011) while controlling for luminance changes. When presented with isoluminant digit sequences, participants\u27 pupillary dilations were synchronized with stimulus onsets when attending, but not when mind-wandering. This replicates Smallwood et al. (2011) and clarifies their finding by demonstrating that stimulus-pupil coupling reflects online cognitive processing beyond sensory gain

Evaluation of signal processing methods for attention assessment in visual content interaction

Eye movements and changes in pupil dilation are known to provide information about viewer’s attention and interaction with visual content. This paper evaluates different statistical and signal processing methods for autonomously analysing pupil dilation signals and extracting information about viewer’s attention when perceiving visual information. In particular, using a commercial video-based eye tracker to estimate pupil dilation and gaze fixation, we demonstrate that wavelet-based signal processing provides an effective tool for pupil dilation analysis and discuss the effect that different image content has on pupil dilation and viewer’s attention

Training-induced Changes in the Dynamics of Attention as Reflected in Pupil Dilation

One of the major topics in attention literature is the attentional blink (AB), which demonstrates a limited ability to identify the second of two targets (T1 and T2) when presented in close temporal succession (200–500 msec). Given that the effect has been thought of as robust and resistant to training for over 2 decades, one of the most remarkable findings in recent years is that the AB can be eliminated after a 1-hr training with a color-salient T2. However, the underlying mechanism of the training effect as well as the AB itself is as of yet still poorly understood. To elucidate this training effect, we employed a refined version of our recently developed pupil dilation deconvolution method to track any training-induced changes in the amount and onset of attentional processing in response to target stimuli. Behaviorally, we replicated the original training effect with a color-salient T2. However, we showed that training without a salient target, but with a consistent short target interval, is already sufficient to attenuate the AB. Pupil deconvolution did not reveal any posttraining changes in T2-related dilation but instead an earlier onset of dilation around T1. Moreover, normalized pupil dilation was enhanced posttraining compared with pretraining. We conclude that the AB can be eliminated by training without a salient cue. Furthermore, our data point to the existence of temporal expectations at the time points of the trained targets posttraining. Therefore, we tentatively conclude that temporal expectations arise as a result of training

Pupil and iris center detection

Tato práce se zabývá zpracováním šedotónových snímků oka za účelem nalezení středu zornice a duhovky, pupilární a limbické hranice. Úvodní část je rešerší na téma pupila a duhovka a změna rozměrů pupily. Jsou tu uvedeny články zabývající se problematikou detekce středu pupily a duhovky, které byly použity jako inspirace pro realizaci vlastních metod v této práci. Úvodní část končí popisem navržených metod, které detekovaly parametry pupily a duhovky ve snímcích databáze CASIA-Iris-Interval. Druhá, praktická část práce, je věnována popisu snímacího systému, který byl sestaven pro získání vlastních snímků oka. Následuje rozbor jednotlivých metod, které byly použity pro rozměření parametrů pupily a duhovky. Jedná se celkem o dvě metody detekce středu pupily a pupilární hranice, jednu metodu určující střed duhovky a limbickou hranici a jednu metodu, která detekuje paramtry pupily a duhovky zároveň. Konec práce je věnován rozboru výsledků jednotlivých metod včetně úspěšnosti detekce a statistické analýzy. Součástí rozboru je také zkoumání změny pupilárního poloměru v závislosti na světelných podmínkách a změny pozice středu pupily při konstrikci a dilataci pupily.This thesis is aimed at image processing to obtain informations about the center of pupil and iris,the pupillar and limbic boundary from grayscale images of the eye. An introduction describes general research in topic of pupil, iris and changes in size of pupil. There are mentioned articles dealing with the detection of the center of pupil and iris. These articles were used as an inspiration for proposal of detection methods used in this work. The introduction ends with description of designed approaches of detection of parameters of pupil and iris in images of CASIA-Iris-Interval database. The second, practical part of this work, is dedicated to description of acquisition system, which was compiled to obtain proper images of eye. Individual analysis of methods used to obtain parameters of pupil and iris follows after that. There are two methods of detection of center of pupil and pupillar boundary, one method determines center of iris and limbic boundary. Last method detects centers and boundaries of pupil and iris at one time. The end of this work is dedicated to analysis of results of designed methods. Analysis includes score of successfulness of detection, statistical analysis, discussion of changes in pupillary diameter depending on the light conditions and changes in position of center of pupil during constriction and dilatation of pupil.

NEW VISUAL ASSESSMENT USING STEADY-STATE VISUAL EVOKED POTENTIAL (SSVEP) AND EYE TRACKING

Master'sMASTER OF ENGINEERIN

Invariant Structural Features of Retrograde Amnesia Affected Memory

Traumatized individuals may use one or several emotional defensive strategies to cope with their experience; one method is via autobiographical amnesia which may influence the efficacy of amnesiac patients’ psychological adjustment during a sensitive period. Little research has addressed the potential of how emotionally invariant structural features may impact the reconsolidation of autobiographical memory, which in turn may support patients to complete successfully psychotherapeutic treatment or intervention. This phenomenological study addressed how lived experiences (i.e., invariant emotional and behavioral conscious states) may play into patients’ transformational memory of some or all of the traumatizing event details. To answer these questions, this study implemented a qualitative phenomenological design formatted around researcher-generated interview protocols and used memory reconsolidation theory, multiple trace theory, and transactional theory of stress and coping to provide context to this study’s findings. A nationwide call for study participants produced a random selection of 15 eligible clinician or patient participants. The Modified Stevick-Colaizzi-Keen phenomenological analysis method was used. The study essence statement revealed three themes combining emotion and cognitive processes, and behaviors prior to trauma memory recall. Not all of the clinician participants became immediately aware of the patient’s recall during treatment. Positive social change implications may include reducted therapeutic duration, accurate and expedient identification of the return of patients’ autobiographical memories, and lowered risk of sudden or unexpected patient psychological or emotional trauma realization

Efeitos da exposição repetida subliminar a estímulos biologicamente relevantes nos estados emocionais

Existem determinados estímulos, como é o caso das cobras, que devido à sua pertinência evolutiva são analisados pré-atencionalmente. Esta relevância traduz-se numa captação atencional mais rápida acompanhada de respostas psicofisiológicas intensas. Contudo, apesar do extenso corpo de literatura reforçar o peso evolutivo deste tipo de estímulos, estudos recentes apontam para resultados incongruentes. Com o objetivo de contribuir para o conhecimento científico neste domínio, a presente tese reúne um conjunto de três estudos empíricos. Os três estudos dão enfoque ao processamento subliminar de estímulos biologicamente relevantes e aos seus efeitos na orientação da atenção e nas respostas psicofisiológicas periféricas e centrais. Baseados em tarefas de atenção visual, os resultados destes estudos suportam a hipótese de que as cobras, quando apresentadas subliminarmente, têm efeitos no orientação atencional (Estudo I), no sistema nervoso periférico (Estudo II), e no sistema nervoso central (Estudo III). De uma forma geral, os resultados suportam a ideia de que imagens de animais ameaçadores tendem a provocar uma resposta diferenciada na atenção e ativação psicofisiológica, mesmo quando apresentados subliminarmente. Os resultados são discutidos à luz de uma perspetiva bioevolutiva, contudo integrativa, recorrendo igualmente a evidências de estudos recentes.Recurrent predatory situations and rival attacks through the evolutionary process may have tagged these situations as “danger to survival”, triggering an emotional fear response. According to this perspective, there are certain stimuli (e.g. snakes) which are pre-attentively processed due to their evolutionary relevance. This is reflected by an enhanced attentional grabbing and more intense psychophysiological responses in comparison to non-relevant stimuli, triggered by the defense system, in order to prepare the organism for action. However, despite the large body of literature supporting the relevance of these types of stimuli, recent studies have shown inconsistent results. Aiming at contributing to the scientific knowledge in this domain, the current thesis brings together a set of three empirical studies. The three experimental following studies focused on the effects of emotional subliminal processing on attentional orienting and on peripheral and central psychophysiological responses. Based on visual attention tasks, the results of these studies support the hypothesis that biologically fear-relevant stimuli subliminally presented have an impact on attentional orienting (Study I), on the peripheral nervous system (Study II), and on the central nervous system (Study III). In general, the results support the idea that the images of threatening animals, tend to provoke a differentiated response in terms of attention and arousal. The results are discussed in light of a bio-evolutionary perspective, yet, in an integrative fashion, by new evidences from recent studies