Posters: Perception I

After an object disappears, the spatial location of the vanishing point of this stimulus is shifted in the direction of motion, a phenomenon known as representational momentum. The present study focusses on the relationship between motion information and spatial location in a cross-modal setting. In two visuotactile experiments, we study how motion information in one modality affects the perceived final location of a motion signal (congruent vs. incongruent left-right motion direction) in the other modality. The results revealed a unidirectional crossmodal influence of motion information on spatial localization performance. Whereas visual motion information influences the perceived final location of the tactile stimulus, the tactile motion information leaves visual localization unaffected. These results therefore extend the existing literature on crossmodal influences on spatial location and are discussed in relation to current theories of crossmodal perceptual integration.

Introduction: Autism spectrum disorders (ASD) are characterized by deficits in social interaction and communication as well as stereotyped and restricted patterns of behavior. Asperger’s syndrome (AS) is a highly functional type of ASD that does not comprise any delay in language development. Research indicates that children with AS show difficulties in speech perception. These difficulties became particularly evident in acoustically deprived conditions. To this day, it is uncertain whether those deficits persist into adulthood. Associated neural mechanisms are also unacquainted. However, those underlying mechanisms are highly significant since social interaction is mainly affected by speech perception. Methods: 17 adult AS and 18 healthy controls (HC) were examined. We used a paradigm in which audiovisual speech stimuli were presented in acoustically deprived conditions. Subject’s performance was quantified by measuring stimulus comprehension. During this task, EEG was recorded from 32 electrodes according to the international 10-20-system. Analysis of EEG-data was performed by BESA research. Results/Discussion: In the present sample, differences in speech comprehension were found between AS and HC. Adult AS continuously showed deficits in speech perception in acoustically deprived conditions. EEG-analysis revealed increased P2 at parietocentral electrodes. This finding was independent of acoustical deprivation. The results indicate enhanced attentional processes in adult AS. These may be used as a compensatory mechanism towards deficits in speech perception. However, a fully normative performance level cannot be achieved. Speech perception remains impaired in acoustically deprived environments.

In previous studies on the distractor-induced blindness paradigm, an inhibitory process of selective attention was found. This effect always occurred when distractors had the same visual characteristics as the following target, leading to a reduced detection rate. Niedeggen, Michael & Hesselmann (2012) showed that with increasing number of distractors a frontal negativity in the ERP increases. In the present study, a similar experimental setup is used with auditory stimuli as distractors and targets, with a visual cue indicating the target. Behavioral data show a comparable reduction of target detection in trials with distractors presented prior to the cue. ERP data show corresponding frontal negativity at 200 ms when the target was not detected and a P3 related to further target and cue processing. Auditory distractors seem to trigger an inhibitory process and lead to a deterioration of the detection rate of auditory targets, which is strikingly similar to the mechanisms assumed for visual stimuli in the distractor-induced blindness paradigm.

Our visual system enables us to perceive and recognize objects with apparent ease and at arresting speed. Recent research shows that the size of an object in the real world is automatically encoded and acts as an organizational principle in the neural representation of objects. Information about the real-world size helps us to navigate and informs the way we interact with objects. Real-world size of objects has been shown to interfere with performance a) when making visual size judgements in a Size-Stroop task and b) when searching for objects, such that objects that are depicted 3-4 times their size (‘giant targets’) are missed more often than the same objects in their actual size. Here, we wanted to replicate these two effects and hypothesized that participants with larger Stroop-effects would also show greater difficulties when searching for mis-scaled giant targets. Forty young adults (mean age: 23.1 yrs) completed both paradigms and showed the hypothesized Size-Stroop effect in two versions (original stimulus (Konkle, & Olivia, 2012) and new stimulus set). This adds to the evidence that real-world size is assessed automatically. To our surprise, we did not find that giant targets are missed more often compared to targets in their actual size, despite using the original stimulus set (Eckstein, Koehler, Welbourne, & Akbas, 2017). We also could not demonstrate a relationship between performances in both tasks, which might be related to the relatively low performance in the search tasks for normally sized objects.

When a target stimulus is briefly presented its visibility can be reduced by a following spatially adjacent mask. This metacontrast masking phenomenon can be related to the operation of three processes, which contribute to target visibility at different stimulus onset-asynchronies (SOA) between the target and the mask. Previous findings suggest that individuals differ regarding the involvement of each of these processes and that each process might be associated to a specific phenomenological experience, which occurs with the corresponding SOAs. With short SOAs, phenomenological reports comprise an integration of target and masking stimuli, indicating the involvement of an integration process. To examine this hypothesis, we compared metacontrast masking to another masking phenomenon, which has been related to an integration process, object substitution masking. Interestingly, however, integration is assumed to impair target visibility in the object substitution paradigm while it is assumed to improve target visibility in metacontrast masking. The temporal dynamic of target visibility was measured in healthy subjects who participated in both paradigms. Factor analyses replicated previous evidence for three processes contributing to target visibility in the case of metacontrast masking. In the case of object substitution masking, evidence suggests two distinct processes. Correlations of individuals’ factor scores reveal the relation between the processes that are involved in the two masking paradigms.

Odor perception is closely linked to emotion processing, influencing the physiological state of the receiver. Certain odors such as mint have additionally been shown to affect cognitive performance (CP). The current study investigates whether this modulation of CP is attributable to reduced sleepiness and increased vigilance and whether it also occurs for lemon odor. We tested 48 participants (37 women, M = 22.3, SD = 3.2 years) in a between subjects design (mint: n = 17, lemon: n = 17, control: n = 14). Participants typed a given text on a computer. Error rate and typing speed were analyzed to assess CP. As a measure of vigilance, the Mackworth Clock Test was applied. Participants’ sleepiness was assessed via the Karolinska Sleepiness Scale. Heart rate variability (HRV) and facial emotional responses were recorded. In the context of mint odor, participants showed increased CP and fewer negative facial emotional responses compared to the control group. No significant effects of mint odor were found on sleepiness, vigilance, and HRV. In contrast, HRV was increased in the context of lemon odor compared to the control group. Results also indicate an activating effect of lemon odor regarding sleepiness and vigilance. Lemon induced more positive facial emotional responses compared to the mint but not the control group. No significant effects of lemon odor on CP was found. Results are in line with prior research, showing mint odor to increase CP. This effect does not rest on reduced sleepiness or increased vigilance. Lemon leads to reverse effects.

Valentine’s norm-based multidimensional facespace (nMDFS) model has been highly influential on face perception research for years. In a recent study, brain correlates (event-related potentials, ERPs) of distance-to-norm ('DTN', P200) and familiarity (N250) processing were found and dissociated, supporting the hypothesis that faces are represented in MDFS corresponding to their DTN (Wuttke & Schweinberger, 2019). As yet, it is unclear whether individual differences in face recognition skills are related to these electrophysiological components of face perception. In the present study, we aimed to replicate P200 DTN and N250 familiarity effects in a sample of high vs. low performers in face recognition and, in addition, we hypothesized that the size of these two effects would be associated with face recognition skills. We further investigated differences in visual processes between these two groups with respect to face processing, object recognition, visual acuity, contrast sensitivity and autism scores (AQ). Results replicated the P200 DTN and the N250 familiarity effect. Crucially, the P200 DTN effect was significantly reduced in low (vs. high) performers in face recognition, and there was a statistically not significant reduction of the N250 familiarity effect in low performers. At the behavioral level, low performers differed from high performers not only in their face processing skills: They also scored lower in object recognition and contrast sensitivity. Overall, the results suggest that norm-based face coding contributes to individual differences in face recognition skills. Moreover, future research should refine possible contributions of other visual processes to facial processing impairments.