Browsing by Subject "Selective Attention"
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Item Data files for dissertation titled "The effect of intense pulsed light on the sensory properties of milk powder and wheat flour and The two-out-five test compared to the triangle test in terms of sensory adaptation, test sensitivity, and selective attention"(2023-07-24) Kang, Myungwoo; kang0237@umn.edu; Kang, Myungwoo; Sensory Science & Food Acceptability Research Group, Department of Food Science and NutritionThis data set contains raw data that was used for statistical analysis in the dissertation titled " The effect of intense pulsed light on the sensory properties of milk powder and wheat flour and The two-out-five test compared to the triangle test in terms of sensory adaptation, test sensitivity, and selective attention"Item The effect of intense pulsed light on the sensory properties of milk powder and wheat flour and The two-out-five test compared to the triangle test in terms of sensory adaptation, test sensitivity, and selective attention(2023-11) Kang, MyungwooIntense pulsed light (IPL) treatment is an emerging technology that has the potential to be used for decontaminating foods as an alternative to thermal processing (Mandal et al., 2020). Researchers (Kramer et al., 2017b; Mahendran et al., 2019; Oms-Oliu et al., 2010) have investigated the feasibility of adapting IPL processing to the food industry to address increasing outbreaks of life-threatening diseases in low-moisture products (e.g., dry milk powder, powdered infant formula, whey powder, wheat flour, and spices). To apply this novel technology at the commercial level, food manufacturers need to develop an optimized IPL system that effectively reduces microorganisms without sacrificing the sensory properties of treated products. Thus, we investigated how IPL processing parameters affected the sensory properties of milk powder and wheat flour. Furthermore, we examined the possible benefits of IPL treatment’s less damaging effect on the sensory properties of treated products compared to conventional Ultraviolet light (UV) treatment. Chapter 1 introduces the principle of IPL treatment and photo-oxidation mechanisms as well as previous studies on light-induced sensory or physicochemical changes in milk products and wheat flour. Chapter 2 presents our experimental study on milk powder. We determined how temperature and exposure time affected the sensory properties of non-fat dry milk while determining at which levels these processing parameters produce sensory differences from the untreated sample. Chapter 3 presents the application of IPL for wheat flour. We determined the effects of IPL processing parameters (voltage, feed rate, and frequency) on the sensory properties of wheat flour. Furthermore, we compared the effect of IPL treatment on the sensory properties of treated samples with those of UV treatment at equivalent efficacy in reducing microorganisms.While examining the IPL and UV treatments, we used the two-out-of-five test method instead of the conventional triangle test. In the two-out-of-five test, judges are presented with five coded samples, two of one product and three of the other. The judges are instructed to sort the samples into two groups according to their similarity. By contrast, the triangle test presents the judges with three samples ‒ two samples of one product and one of the other ‒ and the judges are asked to identify the odd sample among the three. We selected the two-out-of-five test because it requires a small number of participants compared to the triangle test. This is due to the low guessing probability of the two-out-of-five tests (⅒) relative to the triangle test (⅓). However, despite this benefit, there has been a long-standing assumption that the multiple tastings in the two-out-of-five test induce memory load and extreme sensory adaptation, consequently deteriorating the judges’ discrimination ability compared to other tests including two or three samples (Lawless & Heymann, 2010; Meilgaard et al., 2015). Since this assumption has been made without experimental demonstration, we were interested in whether the judges’ discrimination performance would, in fact, decrease in the two-out-of-five test compared to the triangle test. This concern inspired the investigation of the two-out-of-five test, as covered in chapters 4 and 5. Chapter 4 reviews the previous use of the two-out-of-five test in sensory research and the potential adverse effects of multiple tastings on taste adaptation and memory load. Additionally, this chapter reviews the role of selective attention in categorization tasks with visual stimuli as a potential advantage of the two-out-of-five test. Chapter 5 presents our experimental research, where we investigated whether the two-out-of-five test elicited greater taste adaptation and a greater proportion of discriminators compared to the triangle test. In addition, to determine the effectiveness of selective attention in taste perception, we compared the number of attributes used by judges to discriminate among samples between the two-out-of-five test and the triangle test and examined if the use of a single attribute improved judges’ discrimination performance.Item Effects of selective attention on the peripheral auditory system: Otoacoustic emission assays of cochlear function during behavior(2019-03) Beim, JordanSelective attention is an important ability that humans use to navigate a crowded sensory world. In audition, attending to a target while ignoring distractors results in an enhancement of the neural representation of the target and an attenuation of distractors. The neural underpinnings as well as the location of this process within the auditory pathway is not clear. This thesis explores the possibility that the medial olivocochlear reflex, an auditory efferent neural circuit, might aid in selective attention by modulating the gain produced by the cochlea during selective attention. Otoacoustic emissions, small sounds originating in the cochlea, are used to measure changes in cochlear function while participants perform tasks that require attention to either only auditory or only visual stimuli. Experiments assess the replicability of otoacoustic measures made during selective attention, the effect of the perceptual load of attention tasks on these otoacoustic measures, and whether the effects of attention differ with respect to location within the cochlea. Across five experiments results consistently show no evidence for changes in cochlear function during selective attention to auditory or visual stimuli. The results challenge much of the existing literature, which reports small but significant effects of attention, but often in conflicting directions across studies. The results highlight significant variability between individuals in otoacoustic measures of cochlear function, which remains to be explained.Item Learning-induced Attentional Changes in Visual Search(2019-05) Li, ShaExtensive research has shown that prior experience and selection history modulate visual selective attention. Humans are able to learn various types of statistical regularities and use them to optimize allocation of attention. For example, people typically respond faster to visual properties that are predictive of important stimuli (e.g., rewards and search targets) in the past. However, much less is known about whether established attentional modulation persists when the task or visual statistics change. This dissertation aims to understand the effects of visual statistical learning on attention and how such learning adapts to changes in the environment. The first study focuses on reward learning. The results show that participants respond faster to targets that lead to higher reward. But when presented as distractors in a subsequent task, previously high-reward targets do not capture more attention. These findings suggest that monetary reward enhances attentional priority for high-reward targets, but the enhancement dissipates when the prioritized items become distractors in a different task. The second study shows that people are sensitive to occurrence rates of visual features such as color. Participants respond faster to colors that are more frequently associated with the target. However, when colors become equally frequent, people do not always continue prioritizing the previously high-frequency colors. Changes in attentional priority depend on the type of statistical regularities people have learned. The third study examines transfer of the location probability effect across different tasks. Behavioral and eye tracking data suggest that participants prioritize spatial locations that are more likely to contain the target. However, established spatial priority does not transfer to a novel task that requires a different oculomotor search procedure. This dissertation demonstrates that various types of statistical learning affect visual selective attention. However, constraints exist in whether the learning-induced attentional modulation persists in a dynamic environment.