Navigating the world and remembering events require processing information from various sensory modalities. However, research on human spatial memory and navigation is dominated by vision and little is known about the nonvisual senses. According to a recent theoretical framework, spatial memory and navigation evolved together with olfaction to aid navigation. We tasked participants with memorizing locations of odors and sounds in a virtual reality setting, hypothesizing that odor memory representations would disproportionately interfere with sound memory representations. In three recall times (immediate, 15-min delay, and 1-week delay), we tested whether spatial memory of odors would retroactively interfere with sounds. We predicted that performance should decline more in the sensory modality encoded first than in the modality encoded second, due to retroactive interference, especially when sounds are encoded first. Results indicated a decline in spatial memory performance over time, and similar retroactive interference effects from smells and sounds, but no olfactory-specific interference. However, exploratory results indicated that olfactory retroactive interference is apparent in error trials where participants tended to misplace sounds in the vicinity of smells related to the same concepts (e.g., misplacing the sound of a coffee maker at the location of the smell of coffee). There was no similar interference from sounds on odor misplacements, suggesting asymmetry or “olfactory dominance,” at the conceptual level. Our exploratory results suggest that the hypothesized unique role of olfactory retroactive interference might manifest in the type of errors, rather than in overall performance.

The human sense of smell is extraordinarily sensitive, and some argue that a main purpose of olfaction is to localize food sources. Yet, little is known about human spatial memory for odors and the existing literature has never been systematically summarized. In this systematic review and meta-analysis, we evaluated the evidence regarding human abilities to memorize arrangements of objects or routes based on olfactory cues, and compared results to those of other senses. We followed the PRISMA guidelines, searching three databases (PubMed, WoS, Scopus). Using manual and automated (ASReview) screening methods, we identified 24 articles that complied with our inclusion criteria (e.g., olfactory spatial memory task, healthy human adults). Four key results emerged. First, odors can be used as landmarks in the formation of neuro-cognitive maps in both sensory and cognitive brain areas, providing a foundation for spatial memory and navigation abilities. Second, the human ability to memorize locations of odors, especially cues signaling high-calorie food, is indicative of its presumed evolutionary role in foraging. Third, odor-recognition and odor-context-place association might stem from overlapping memory processes. Fourth, olfactory targeted training enhances olfactory spatial memory and shows transfer to other modalities and cognitive domains. Seven articles that compared performances in olfactory versus visual spatial memory were eligible for meta-analysis. The analysis was carried out using the standardized mean difference (i.e., Glass’s estimator) as the outcome measure. A random-effects model was fitted to the data. Results showed that olfactory spatial memory is less effective than visual memory ( = −0.48, 95% CI [ − 0.77, − 0.19]). Notably, two studies exhibiting the largest differences between sensory modalities were either evaluated as of moderate quality or included older participants. Furthermore, all included studies varied in the methods and materials used. Thus, we suggest that addressing methodological variations across studies and investigating the neural mechanisms will be pivotal for further advancing this research field.

TIME is a highly abstract concept and prevalent in languages worldwide. Cross-cultural and cross-linguistic research suggests that TIME is embodied dissimilarly in different languages. Still the literature has not received sufficient attention in examining the differences. This study aimed to identify and compare how TIME is metaphorically represented and embodied worldwide. We investigated 14 languages; Arabic, Assamese, Chinese, English, Finnish, French, German, Japanese, Kikuyu, Persian, Polish, Russian, Spanish, and Swedish, which represent nine language families. The metaphors were categorized conceptually as TIME IS AN ORGANISM, TIME IS MOTION, TIME IS SPACE, and TIME IS A VALUABLE COMMODITY. We employed a two-part paper-based task. The first part consisted of generation of metaphor items and the second part consisted of a valence rating task. The key variables considered were 'metaphor category' and 'language family' while controlling for demographic variables such as gender, age and handedness. Data from 513 participants were collected. Results showed a significant association between language categories and the valences of time metaphors. The data of this study suggest that within the languages of a certain category, there might be some similarity between the valences of words that are used to realize a given conceptual metaphor.

Specific phobia can be treated successfully with exposure therapy. Although exposure therapy has strong effects on self-reported ratings and behavioral avoidance, effects on measures derived from electroencephalography (EEG) are scant and unclear. To fill this gap, spider-phobic individuals received either in-vivo or virtual reality exposure treatment. Patients were tested twice (one week before and after treatment), and control subjects once. In each session, EEG was recorded to spider pictures as well as other positive, negative, and neutral pictures. During EEG recording, participants performed a simple detection task while task-irrelevant pictures were shown in the background. The task was used to reduce potential confounding effects from shifts of attention. After the task, subjects were shown the pictures again and rated each in terms of their emotional reaction (arousal and pleasantness). The results showed that before treatment, patients rated spiders as more negative than did control subjects. Patients also showed elevated early posterior negativity (EPN) and late positive potential (LPP) to spiders. After treatment, the negative emotional ratings of spiders were substantially reduced. Critically, Bayesian analyses suggested that EPN and LPP were unaffected by treatment and that the treatment groups did not differ in their responses (EPN, LPP, and ratings). These findings suggest that the effects of in vivo and virtual reality exposure therapy are similar and that the initial stages of motivated attention (EPN and LPP) are unaffected by treatment.

Ignoring background sounds while focusing on a visual task is a necessary ability in everyday life. If attentional resources are shared between modalities, processing of task-irrelevant auditory information should become attenuated when attentional capacity is exhausted by visual demands. According to earlyfilter theory, top-down attenuation of auditory responses is possible at various stages of the auditory pathway through multiple recurrent loops. Furthermore, the adaptive filtering model of selective attention suggests that filtering occurs early when concurrent visual tasks are demanding (e.g., high load) and late when tasks are easy (e.g., low load). This study examined effects of visual load on auditory steady state responses (ASSRs) to determine where in the auditory pathway the filtering occurs. Subjects performed a visual task with three levels of load (no, low, and high) while ignoring task-irrelevant sounds. The auditory stimuli were 500-Hz tones amplitude-modulated at 20 Hz, 40 Hz, or 80 Hz to target different processing stages of the auditory pathway. Results from bayesian analyses suggest that ASSRs are unaffected by visual load. These findings also suggest that attentional resources are modality specific and that the attentional filter of auditory processing does not vary with visual task demands.

In daily life, people need to be able to focus on a task while ignoring any task-irrelevant background noise. For example, people who work in an open-space office may have to work on a report while ignoring the background talk among co-workers. Theories of attention argue that processing of task-irrelevant auditory information should become attenuated when attentional capacity is exhausted by task-relevant stimuli, for example a visual task. According to early-filter theory, top-down attenuation of auditory responses is possible at various stages of the auditory pathway through multiple recurrent loops. Furthermore, the adaptive filtering model of selective attention suggests that filtering occurs early when concurrent visual tasks are demanding (e.g., high load) and late when tasks are easy (e.g., low load).

The main aim of this thesis was to investigate whether auditory processing is attenuated during concurrent visual load manipulation, and if so, at which stage of the auditory pathway. Recurrent loops that are present throughout the entire auditory pathway should allow top-down modulation of even earliest responses, especially when accompanied by a highly demanding task. Recording these auditory responses during concurrent visual tasks with different levels of load could potentially show at which stages of auditory processing the filtering happens when the task demands are high or low, or there is no task at all.

This thesis tested the effects of visual load manipulation on the responses originating from different stages of the auditory pathway: mismatch negativity (MMN) to duration in Study I, MMN to frequency in Study III, auditory steady-state responses (ASSRs) to a 40-Hz modulation frequency in Study IV, and ASSRs to 20-, 40-, and 80-Hz modulation frequencies in Study V. Additionally, Study II compared different control conditions (cascade vs. no-repetition control) for evoking MMN to find a design that reduces confounds in the MMN. Results of Study II showed that cascade and no-repetition control are comparable control conditions for evoking MMN.

For the effects of visual load manipulation on auditory MMN (low vs. high load), results showed moderate evidence for the effect of load on duration MMN and moderate evidence for no effect of load on frequency MMN. However, results for the duration MMN might be confounded by physical differences between the low load and high load conditions in the visual task, and by a biased oddball paradigm used to evoke the MMN. Thus, it is most likely that auditory MMN is not affected by visual load (low vs. high).

For the effects of visual load on ASSRs (no, low, and high load), results showed moderate to strong evidence for no effects of load manipulation on ASSRs, but some comparisons were inconclusive. The convincing evidence obtained in Studies IV and V points to the robustness of ASSRs against visual load manipulation.

Because it is most likely that neither MMN nor ASSRs are affected by visual load manipulation, results presented in this thesis support the idea that attentional resources are modality specific. Because it is possible that filtering occurs at one stage of auditory processing and does not change with the concurrent task demands, the present results do not rule out the early-filter theory. However, results are inconsistent with the adaptive filtering model because filtering of task-irrelevant responses does not vary with the demands of the concurrent task.

The auditory pathway consists of multiple recurrent loops of afferent and efferent connections that extend from the cochlea up to the prefrontal cortex. The early-filter theory proposes that these loops allow topdown filtering of early and middle latency auditory responses. Furthermore, the adaptive filtering model suggests that filtering of irrelevant auditory stimuli should start lower in the pathway during more demanding tasks. If so, the 40-Hz auditory steady state responses (ASSRs) to irrelevant sounds should be affected by top-down crossmodal attention to a visual task, and effects should vary with the load of the visual task. Because few studies have examined this possibility, we conducted two preregistered studies that manipulated visual load (Study 1: N = 43, Study 2: N = 45). Study 1 used two levels (low and high), and Study 2 used four levels (no, low, high, and very high). Subjects were asked to ignore a 500-Hz taskirrelevant tone that was amplitude-modulated to evoke 40-Hz ASSRs. Results from Bayesian analyses provided moderate to extreme support for no effect of load (or of task) on ASSRs. Results also supported no interaction with time (i.e., over blocks, over minutes, or with changes in ASSRs that were synchronized with the onset of the visual stimuli). Further, results provided moderate support for no correlation between effects of load and working memory capacity. Because the present findings support the robustness of ASSRs against manipulations of crossmodal attention, they are not consistent with the adaptive filtering model.

The mismatch negativity (MMN) has been widely studied with oddball tasks to index processing of unexpected auditory change. The MMN is computed as the difference of deviant minus standard and is used to capture the pattern violation by the deviant. However, this oddball MMN is confounded because the deviant differs physically from the standard and is presented less often. To improve measurement, the same tone as the deviant is presented in a separate condition. This control tone is equiprobable with other tones and is used to compute a corrected MMN (deviant minus control). Typically, the tones are in random order except that consecutive tones are not identical (no-repetition rule). In contrast, a recent study on frequency MMN presented tones in a regular up-and-down sequence (cascade rule). If the cascade rule is detected more easily than the no-repetition rule, there should be a lower risk of a confounding MMN within the cascade condition. However, in previous research, the cascade and no-repetition conditions differed not only in the regularity of the tone sequence but also in number of tones, frequency range, and proportion of tones. We controlled for these differences to isolate effects of regularity in the tone sequence. Results of our preregistered analyses provided moderate evidence (BF01>6) that the corrected MMN did not differ between cascade and no-repetition conditions. These findings imply that no-repetition and cascade rules are processed similarly and that the no-repetition condition provides an adequate control in frequency MMN.

Listeners have limited access to spatial information in lagging sound, a phenomenon known as discrimination suppression. It is unclear whether discrimination suppression works differently for interaural time differences (ITDs) and interaural level differences (ILDs). To explore this, three listeners assessed the lateralization (left or right) and detection (present or not) of lag clicks with a large fixed ITD (350 mu s) or ILD (10 dB) following a diotic lead click, with inter-click intervals (ICIs) of 0.125-256 ms. Performance was measured on a common scale for both cues: the lag-lead amplitude ratio [dB] at 75% correct answers. The main finding was that the lateralization thresholds, but not detection thresholds, were more strongly elevated for ITD-only than ILD-only clicks at intermediate ICIs (1-8 ms) in which previous research has found the strongest discrimination suppression effects. Altogether, these findings suggest that discrimination suppression involves mechanisms that make spatial information conveyed by lag-click ITDs less accessible to listeners than spatial information conveyed by lag-click ILDs.

The mismatch negativity (MMN) has been of particular interest in auditory perception because of its sensitivity to auditory change. It is typically measured in an oddball task and is computed as the difference of deviant minus standard tones. Previous studies suggest that the oddball MMN can be reduced by crossmodal attention to a concurrent, difficult visual task. However, more recent studies did not replicate this effect. Because previous findings seem to be biased, we preregistered the present study and used Bayesian hypothesis testing to measure the strength of evidence for or against an effect of visual task difficulty. We manipulated visual perceptual load (high and low load). In the task, the visual stimuli were identical for both loads to avoid confounding effects from physical differences of the visual stimuli. We also measured the corrected MMN because the oddball MMN may be confounded by physical differences between deviant and standard tones. The corrected MMN is obtained with a separate control condition in which the same tone as the deviant (critical tone) is equiprobable with other tones. The corrected MMN is computed as deviant minus critical tones. Furthermore, we assessed working memory capacity to examine its moderating role. In our large sample (N = 49), the evidential strength in support of no effect of visual load was moderate for the oddball MMN (9.09 > BF01 > 3.57) and anecdotal to moderate for the corrected MMN (4.55 > BF01 > 2.17). Also, working memory capacity did not correlate with the visual load effect on the oddball MMN and the corrected MMN. The present findings support the robustness of the auditory frequency MMN to manipulations of crossmodal, visual attention and suggest that this relationship is not moderated by working memory capacity.