The saliency map is a computational model and has been constructed for simulating human saliency processing, e.g. pop-out target detection (e.g. Itti & Koch, 2000). In this study the spatial structure on the saliency map was investigated. It is proposed that the saliency map is structured into processing units whose size is increasing with retinal eccentricity. In two experiments the distance between a target in the stimulus and an irrelevant structure in the mask was varied systematically. Our findings had two main points. Firstly, in texture segmentation tasks the saliency signals from two texture irregularities interfere, when these irregularities appear within a critical spatial distance. Second, the critical distances increase with target eccentricity. The eccentricity-dependent critical distances can be interpreted as crowding effects. It is assumed that additionally to the target eccentricity, also the strength of a saliency signal can determine the spatial area of its impairing influence.
Background. In stress research, economic instruments for introducing acute stress responses are needed. In this study, we investigated whether the socially evaluated cold-pressor group test (SECPT-G) induces salivary alpha-amylase and/or cortisol responses in the general population and whether this is associated with anthropometric, experimental, and lifestyle factors. Methods.A sample of 91 participants from the general population was recruited. Salivary cortisol and alpha-amylase (sAA) levels were assessed prior to (t0), immediately after (t 1 ), and ten minutes after the SECPT-G (t 2 ). Results.A robust cortisol increase was found immediately after the SECPT-G, which further increased between t 1 and t 2 . This was independent of most of the control variables. However, men showed a trend towards higher cortisol increases than women (p = .005). No sAA responses were found at all. However, sAA levels were dependent on measurement time point with highest levels between 9 pm and 9:30 pm. Participants who immersed their hands into the ice water for the maximally allowed time of three minutes showed higher sAA levels at all time points than participants who removed their hands from the water earlier.Conclusions. We conclude that the SECPT-G is a good means of an acute stress test when cortisol -but not necessarily sAA -responses are intended.PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.27658v2 | CC BY 4.0 Open Access | recAbstract 17 Background. In stress research, economic instruments for introducing acute stress responses are 18 needed. In this study, we investigated whether the socially evaluated cold-pressor group test 19 (SECPT-G) induces salivary alpha-amylase and/or cortisol responses in the general population 20 and whether this is associated with anthropometric, experimental, and lifestyle factors. 21 Methods. A sample of 91 participants from the general population was recruited. Salivary 22 cortisol and alpha-amylase (sAA) levels were assessed prior to (t 0 ), immediately after (t 1 ), and 23 ten minutes after the SECPT-G (t 2 ). 24 Results. A robust cortisol increase was found immediately after the SECPT-G, which further 25 increased between t 1 and t 2 . This was independent of most of the control variables. However, 26 men showed a trend towards higher cortisol increases than women (p = .005). No sAA responses 27 were found at all. However, sAA levels were dependent on measurement time point with highest 28 levels between 9 pm and 9:30 pm. Participants who immersed their hands into the ice water for 29 the maximally allowed time of three minutes showed higher sAA levels at all time points than 30 participants who removed their hands from the water earlier. 31 Conclusions. We conclude that the SECPT-G is a good means of an acute stress test when 32 cortisol -but not necessarily sAA -responses are intended. 33 34 35 36
Speech fluency can be impaired in stressful situations. In this study, it was investigated whether a verbal fluency task by itself, i.e. without the presence of any further stressors, induces responses of the hypothalamic-pituitary adrenal (HPA) axis and of the sympathetic nervous system (SNS). The sample consisted of n = 85 participants (68.2% female; 33.3 ± 15.2 years) who performed two consecutive verbal fluency tasks for two minutes each. The categories were either 'stress' or 'disease' and 'animals' or 'foods' which were presented in a randomized order. Three saliva samples were collected, prior to the task (t 0), immediately after (t 1), and ten minutes after it (t 2). Salivary α-amylase and cortisol were assessed. Furthermore, blood pressure, heart rate, and ratings of actual stress perception, level of effort, and tiredness were measured. The verbal fluency task induced a HPA axis response with a maximum cortisol level at t 2 which was independent of task performance. Furthermore, perceived stress and effort, as well as tiredness increased after the task. Moreover, tiredness immediately after the task was negatively correlated with task performance. No α-amylase, blood pressure, or heart rate, and therefore SNS, responses were found. Implications for the integrated specificity model are discussed. We conclude that a verbal fluency task acts like an acute stressor that induces a cortisol and a perceived stress response without the need for further (e.g., social-evaluative) stress components. Therefore, it is a less time-consuming alternative to other stress tasks that can be used in field studies with little effort.
Background In stress research, economic instruments for introducing acute stress responses are needed. In this study, we investigated whether the socially evaluated cold-pressor group test (SECPT-G) induces salivary alpha-amylase (sAA) and/or cortisol responses in the general population and whether this is associated with anthropometric, experimental, and lifestyle factors. Methods A sample of 91 participants from the general population was recruited. Salivary cortisol and sAA levels were assessed prior to (t0), immediately after (t1), and 10 min after the SECPT-G (t2). Results A robust cortisol increase was found immediately after the SECPT-G, which further increased between t1 and t2. This was independent of most of the control variables. However, men showed a trend toward higher cortisol increases than women (p = 0.005). No sAA responses were found at all. However, sAA levels were dependent on measurement time point with highest levels between 9 pm and 9:30 pm. Participants who immersed their hands into the ice water for the maximally allowed time of 3 min showed higher sAA levels at all time points than participants who removed their hands from the water earlier. Conclusions We conclude that the SECPT-G is a good means of an acute stress test when cortisol—but not necessarily sAA—responses are intended.
Abstract-In three texture segmentation experiments a target patch had to be detected. We studied the impact of a task-irrelevant patch in the backward mask on detection performance, and especially the modulating effects of its spatial distance to the target. It was assumed that the signals of the two texture irregularities interact as a function of their spatial distance. Experiment 1 revealed that the taskirrelevant patch impaired target detection only when the distance was small. In Experiments 2 and 3 with systematically varying distances, detection performance increased linearly with distance until a maximum point. If the task-irrelevant patch appeared outside of a critical distance, performance did not increase further with increasing distance. Our findings are discussed in terms of the biased competition account. It is proposed that the critical distance may correspond to the average receptive field size of a cortical area that is critical for target detection.
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