Comparing autonomic responses between learned and unlearned stimuli presented with equal probability

Comparing autonomic responses between learned and unlearned stimuli presented with equal probability

International Journal of Psychophysiology 94 (2014) 120–261 been reporting their associations to this stimuli. Two types of stimuli primed all the im...

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International Journal of Psychophysiology 94 (2014) 120–261

been reporting their associations to this stimuli. Two types of stimuli primed all the images: a) images of familiar, common objects and b) images of globally unfamiliar, abstract objects. Targets were presented for 400 ms, primes — for 325 ms, without any interval between them. The second stage was held 1–3 days after the first: we recorded ERPs in response to the repeatedly presented targets. Participants were instructed to recall their associations. Images were presented for 400 ms, without primes. Repeated measures ANOVAs were computed for the locations Fz, Cz and Pz only with following factors: two prime types (familiar vs. unfamiliar) × 32 targets × 20 subjects for each latency window. The first stage results showed an enhanced ERP positivity (300– 600 ms temporal window) for the targets primed by globally unfamiliar stimuli as compared to the targets primed by familiar stimuli (F(1,1278) = 5.4308, p = 0.0199). There is the same trend in the second stage results: repeated presentation of images that were primed by the globally unfamiliar stimuli on the first stage is followed by increase of ERP positivity in the 450–525 temporal window (F(1,1278) = 8.3872, p = 0.0038), which is related to the decrease of neural activity (Grill-Spector et al., 2006). We explain the results in terms of Bayesian “explaining away” approach (Friston, 2003). According to it, priming can be regarded as a prediction error minimization caused by “obtruding” a definite prediction through the prime presentation. However, the globally unfamiliar stimulus presentation doesn't activate any memory trace, so it doesn't lead to any prediction. While familiar stimulus presentation suppresses a set of sensory inputs which are not related to it, unfamiliar stimulus presentation doesn't influence the subsequent information processing. The research was supported by the grant of Saint Petersburg State University 8.38.303.2014. doi:10.1016/j.ijpsycho.2014.08.922

Comparing autonomic responses between learned and unlearned stimuli presented with equal probability Michiko Tsuneokaa, Izumi Matsudaa, Tokihiro Ogawaa, Yohtaro Takanob a National Research Institute of Police Science, Japan b The University of Tokyo Graduate school of Human and Sociology, Japan Relationship between memory and autonomic responses has been examined in the concealed information test (CIT) studies. However, in the CIT, not only memory but also other factors, for instance, orienting response and intention to conceal, may influence autonomic responses. In addition, a learned stimulus in the CIT is typically presented as an infrequent stimulus. Thus we have a question, “What is the effect of memory on autonomic responses?” In this study, we investigate whether autonomic responses are different between learned and unlearned stimuli presented with equal probability. We also examine the relationship of autonomic responses with time for recognition and subjective confidence for their recognition decision. Fifty-five people participated in our experiment. We used 60 twocharacter meaningless words, half for learned stimuli and the other half for unlearned stimuli. In the learning task, each stimulus was presented on a PC display for 5 s in random order, and participants learned it. Next, participants performed a Brown–Peterson task. Then participants received memory task. In this task, both learned and unlearned stimuli were presented with equal probability. This task included 4 phases: recognition, keeping still, rating confidence for their recognition decision, and Remember–Know judgment. In the recognition phase, participants were instructed to answer whether each stimulus was a learned one by pressing a key as fast and accurately as possible. We measured reaction time (RT) in this phase

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and autonomic responses such as skin conductance, heart rate, and normalized pulse volume throughout this task. We analyzed these autonomic responses from 15 s after recognition judgment. The result revealed that only heart rate showed a significant difference: it decelerated more for unlearned stimuli than for learned ones. We also calculated area under the ROC curve for each participant and each measure. The 95% confidence interval of the area showed that only heart rate significantly discriminated between learned and unlearned stimuli. We also considered correlation of each autonomic response with RT and subjective confidence, but no meaningful correlation was found. We suggest that lower heart rate for unlearned stimuli may reflect heightened parasympathetic activity. On the other hand, previous studies of the CIT have shown such difference in not only the heart rate but also other autonomic responses. Such difference may be derived from recognition difficulty; in our study, recognition was difficult but in others was not. In the future, we intend to consider autonomic responses with an easier recognition task. doi:10.1016/j.ijpsycho.2014.08.923

Involvement of eye movement in forward and backward recalls on a spatial working memory task Yuhei Oia, Yoshifumi Ikedab, Hideyuki Okuzumia, Mitsuru Kokubuna Faculty of Education, Tokyo Gakugei University, Japan b Department of Special Needs Education, Joetsu University of Education, Japan

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Several lines of research suggest that eye movement is involved in spatial working memory, but its relation remains unclear. This study was designed to investigate the relation between eye movement and spatial working memory. This study particularly examines whether fixation contributes to recall performance in a spatial working memory task. For this study, 24 participants (12 male, 12 female; mean age 21.5 yr) performed a spatial working memory task in which seven black squares to be remembered were presented. The targets were presented for 1000 ms, one at a time, at different locations on a computer screen. Participants were asked to recall the locations in forward or backward order. In each recall direction, two conditions were given. Participants were instructed to memorize the locations and their order, maintaining fixation on each target until its disappearance (fixation condition) or as they pleased regarding their eye movements (free condition). After the memory task, participants performed a fixation task as a baseline in which the displays were the same as the memory task, but only fixation on targets was required. Eye movements were recorded during the tasks. The fixation durations were computed by summing up the durations of all fixations on each target during its presentation. Recall was scored according to a strict serial criterion. The following are the results. (a) In terms of the nature of fixation on the memory task, fixation durations decreased gradually as targets were presented, even in the fixation condition. (b) Fixation durations were significantly greater in the fixation condition relative to the free condition at all serial positions for both forward and backward recalls, except at serial position 2 for forward recall. (c) No significant difference was found in memory performance in forward recall between conditions despite the increments of fixation durations in the fixation condition. (d) For backward recall, maintaining fixation was significantly beneficial for recall at serial position 6 but significantly disruptive at serial positions 1 and 3. This study indicates that eye movement is important for spatial working memory because fixation durations decreased as targets