I urval från Stockholms universitets publikationsdatabas

• Comparing Echo-Detection and Echo-Localization in Sighted Individuals

  2021. Carlos Tirado (et al.). Perception 50 (4), 308-327

  Artikel

  Echolocation is the ability to gather information from sound reflections. Most previous studies have focused on the ability to detect sound reflections, others on the ability to localize sound reflections, but no previous study has compared the two abilities in the same individuals. Our study compared echo-detection (reflecting object present or not?) and echo-localization (reflecting object to the left or right?) in 10 inexperienced sighted participants across 10 distances (1-4.25 m) to the reflecting object, using an automated system for studying human echolocation. There were substantial individual differences, particularly in the performance on the echo-localization task. However, most participants performed better on the detection than the localization task, in particular at the closest distances (1 and 1.7 m), illustrating that it sometimes may be hard to perceive whether an audible reflection came from the left or right.

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• Individual differences in the ability to access spatial information in lag-clicks

  2021. Carlos Tirado, Billy Gerdfeldter, Mats E. Nilsson. Journal of the Acoustical Society of America 149 (5), 2963-2975

  Artikel

  It may be difficult to determine whether a dichotic lag-click points to the left or right when preceded by a diotic lead-click. Previous research suggests that this loss of spatial information is most prominent at inter-click intervals (ICIs) <10 ms. However, a study by Nilsson, Tirado, and Szychowska [(2019). J. Acoust. Soc. Am. 145, 512–524] found support for loss of spatial information in lag-clicks at much longer ICIs using a stimulus setup differing from those in previous research. The present study used a setup similar to that of the Nilsson, Tirado, and Szychowska study [(2019). J. Acoust. Soc. Am. 145, 512–524] to measure 13 listeners' ability to lateralize (left versus right) and detect (present versus absent) the lag-click in lead–lag click pairs with ICIs of 6–48 ms. The main finding was distinct individual differences in performance. Some listeners could lateralize lag-clicks all the way down to their detection threshold, whereas others had lateralization thresholds substantially higher than their detection thresholds, i.e., they could not lateralize lag-clicks that they could easily detect. Two such listeners trained for 30 days and managed to improve their lateralization thresholds to reach their detection thresholds, but only at longer ICIs (>20 ms), suggesting different mechanisms underlying lag-click lateralization at short versus long ICIs.

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• The psychophysics of human echolocation

  2021. Carlos Tirado Aldana.

  Avhandling (Dok)

  Echolocation is the capacity to detect, localize, discriminate, and, overall, gather spatial information from sound reflections. Since we began studying it in humans, we have learned several things. First, most humans can echolocate to some degree. Second, the capacity to echolocate is related to: the type and size of the object that the individual is trying to echolocate; how well the individual can use self-generated or artificial signals; and the distance to the object. Third, the blind tend to perform better than the sighted, although some sighted individuals can perform as well as the blind. It has been speculated that expert echolocators are capable of unlearning the precedence effect (PE), which is the tendency of our auditory system to prioritize spatial information coming from the first wave front instead of the spatial information from the second wave front. This would allow them to obtain more spatial information from echoes, but there is little research linking the PE to echolocation skills, which is why my thesis research has explored this matter. Another contribution of my thesis research was to introduce two new concepts: echo-detection and echo-localization. Echo-detection is the ability to detect an object using echoes as the main cue (“Is the object there, yes or no?”), whereas echo-localization is the ability both to detect and also localize an object using echoes as the main cue (“Is the object situated to the right or left?”). The reason for dividing echolocation into these two tasks is that detecting an echo does not necessarily entail knowing its location. No previous study has compared these two distinct abilities. Echo-detection and echo-localization, though linked to each other, could be influenced by different mechanisms. 

  The aim of this thesis was to explore individual differences in echo-detection, echo-localization, and other fundamental psychoacoustic abilities (i.e., PE and different types of masking) in inexperienced, sighted individuals. This included using a novel tool to train and assess echolocation skills: the Echobot. The Echobot is a machine that automates stimulus presentation. It allows an aluminum disk to be moved to different distances and different echolocation signals to be tested simultaneously. Its main advantage consists of facilitating the use of rigorous psychophysical methods that would otherwise take a long time to perform correctly. Studies I and II focused on individual differences in fundamental hearing abilities that are prerequisites for echo-detection and echo-localization (i.e., PE components and different types of masking). Studies III and IV focused on using the Echobot to study individual performance differences in echo-detection and echo-localization tasks. Overall, the results indicate that echolocation was possible for most participants, regardless of the method or signal used. There were substantial individual differences, and a performance gap between echo-detection and echo-localization appeared in several individuals. Echo-localization was usually more difficult than echo-detection, since spatial information was the hardest to retrieve from the localization tasks. It was possible to close the task performance gap in some individuals through training, but only for time intervals between direct and reflected sound of >20 ms, for which the PE might not operate. Hence, the possibility of “unlearning” the PE to improve echolocation skills remains speculative. Finally, the Echobot proved useful for studying echolocation. Taken together, these results suggest that independent mechanisms make the localization of spatial information more difficult than pure detection. However, in long-inter-click-interval (ICI) conditions, the neural mechanisms are likely mediated by attention and cognitive processes, which are more plastic, and participants can learn to obtain echo-localization information as effectively as echo-detection information. In short-ICI conditions, neural mechanisms seem more related to peripheral and temporal processing, which are potentially less plastic. Further research into individual differences in temporal processing, using brain-imaging techniques such as EEG, might help us understand the different mechanisms influencing echo-detection and echo-localization.

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• Your Face and Moves Seem Happier When I Smile Facial Action Influences the Perception of Emotional Faces and Biological Motion Stimuli

  2020. Fernando Marmolejo-Ramos (et al.). Experimental psychology (Göttingen) 67 (1), 14-22

  Artikel

  In this experiment, we replicated the effect of muscle engagement on perception such that the recognition of another's facial expressions was biased by the observer's facial muscular activity (Blaesi & Wilson, 2010). We extended this replication to show that such a modulatory effect is also observed for the recognition of dynamic bodily expressions. Via a multitab and within-subjects approach, we investigated the emotion recognition of point-tight biological walkers, along with that of morphed face stimuli, white subjects were or were not holding a pen in their teeth. Under the pen-in-the-teeth condition, participants tended to tower their threshold of perception of happy expressions in facial stimuli compared to the no-pen condition, thus replicating the experiment by Blaesi and Wilson (2010). A similar effect was found for the biological motion stimuli such that participants Lowered their threshold to perceive happy walkers in the pen-in-the-teeth condition compared to the no-pen condition. This pattern of results was also found in a second experiment in which the no-pen condition was replaced by a situation in which participants held a pen in their lips (pen-in-tips condition). These results suggested that facial muscular activity alters the recognition of not only facial expressions but also bodily expressions.

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• Psychoacoustic evidence for stronger discrimination suppression of spatial information conveyed by lag-click interaural time than interaural level differences

  2019. Mats E. Nilsson, Carlos Tirado, Malina Szychowska. Journal of the Acoustical Society of America 145 (1), 512-524

  Artikel

  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.

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• Spatial-numerical associations

  2019. Stefan Buijsman, Carlos Tirado. Quarterly Journal of Experimental Psychology 72 (10), 2423-2436

  Artikel

  During the last decades, there have been a large number of studies into the number-related abilities of humans. As a result, we know that humans and non-human animals have a system known as the approximate number system that allows them to distinguish between collections based on their number of items, separately from any counting procedures. Dehaene and others have argued for a model on which this system uses representations for numbers that are spatial in nature and are shared by our symbolic and non-symbolic processing of numbers. However, there is a conflicting theoretical perspective in which there are no representations of numbers underlying the approximate number system, but only quantity-related representations. This perspective would then suggest that there are no shared representations between symbolic and non-symbolic processing. We review the evidence on spatial biases resulting from the activation of numerical representations, for both non-symbolic and symbolic tests. These biases may help decide between the theoretical differences; shared representations are expected to lead to similar biases regardless of the format, whereas different representations more naturally explain differences in biases, and thus behaviour. The evidence is not yet decisive, as the behavioural evidence is split: we expect bisection tasks to eventually favour shared representations, whereas studies on the spatial-numerical association of response codes (SNARC) effect currently favour different representations. We discuss how this impasse may be resolved, in particular, by combining these behavioural studies with relevant neuroimaging data. If this approach is carried forward, then it may help decide which of these two theoretical perspectives on number representations is correct.

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• The Allocation of Valenced Percepts Onto 3D Space

  2019. Fernando Marmolejo-Ramos (et al.). Frontiers in Psychology 10

  Artikel

  Research on the metaphorical mapping of valenced concepts onto space indicates that positive, neutral, and negative concepts are mapped onto upward, midward, and downward locations, respectively. More recently, this type of research has been tested for the very first time in 3D physical space. The findings corroborate the mapping of valenced concepts onto the vertical space as described above but further show that positive and negative concepts are placed close to and away from the body; neutral concepts are placed midway. The current study aimed at investigating whether valenced perceptual stimuli are positioned onto 3D space akin to the way valenced concepts are positioned. By using a unique device known as the cognition cube, participants placed visual, auditory, tactile and olfactory stimuli on 3D space. The results mimicked the placing of valenced concepts onto 3D space; i.e., positive percepts were placed in upward and close-to-the-body locations and negative percepts were placed in downward and away-from-the-body locations; neutral percepts were placed midway. These pattern of results was more pronounced in the case of visual stimuli, followed by auditory, tactile, and olfactory stimuli. Significance Statement Just recently, a unique device called the cognition cube (CC) enabled to find that positive words are mapped onto upward and close-to-the-body locations and negative words are mapped onto downward and away-from-the-body locations; neutral words are placed midway. This way of placing words in relation to the body is consistent with an approach-avoidance effect such that good and bad things are kept close to and away from one's body. We demonstrate for the very first time that this same pattern emerges when visual, auditory, tactile, and olfactory perceptual stimuli are placed on 3D physical space. We believe these results are significant in that the CC can be used as a new tool to diagnose emotion-related disorders.

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• The Echobot

  2019. Carlos Tirado, Peter Lundén, Mats E. Nilsson. PLOS ONE 14 (10)

  Artikel

  Echolocation is the detection and localization of objects by listening to the sounds they reflect. Early studies of human echolocation used real objects that the experimental leader positioned manually before each experimental trial. The advantage of this procedure is the use of realistic stimuli; the disadvantage is that manually shifting stimuli between trials is very time consuming making it difficult to use psychophysical methods based on the presentation of hundreds of stimuli. The present study tested a new automated system for stimulus presentation, the Echobot, that overcomes this disadvantage. We tested 15 sighted participants with no prior experience of echolocation on their ability to detect the reflection of a loudspeaker-generated click from a 50 cm circular aluminum disk. The results showed that most participants were able to detect the sound reflections. Performance varied considerably, however, with mean individual thresholds of detection ranging from 1 to 3.2 m distance from the disk. Three participants in the loudspeaker experiment also tested using self-generated vocalization. One participant performed better using vocalization and one much worse than in the loudspeaker experiment, illustrating that performance in echolocation experiments using vocalizations not only measures the ability to detect sound reflections, but also the ability to produce efficient echolocation signals. Overall, the present experiments show that the Echobot may be a useful tool in research on human echolocation.

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• The allocation of valenced concepts onto 3D space

  2018. Fernando Marmolejo-Ramos (et al.). Cognition & Emotion 32 (4), 709-718

  Artikel

  The valence-space metaphor research area investigates the metaphorical mapping of valenced concepts onto space. Research findings from this area indicate that positive, neutral, and negative concepts are associated with upward, midward, and downward locations, respectively, in the vertical plane. The same research area has also indicated that such concepts seem to have no preferential location on the horizontal plane. The approach-avoidance effect consists in decreasing the distance between positive stimuli and the body (i.e. approach) and increasing the distance between negative stimuli and the body (i.e. avoid). Thus, the valence-space metaphor accounts for the mapping of valenced concepts onto the vertical and horizontal planes, and the approach-avoidance effect accounts for the mapping of valenced concepts onto the depth plane. By using a cube conceived for the study of allocation of valenced concepts onto 3D space, we show in three studies that positive concepts are placed in upward locations and near the participants' body, negative concepts are placed in downward locations and far from the participants' body, and neutral concepts are placed in between these concepts in both planes.

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• The strength of weak embodiment

  2018. Carlos Tirado (et al.). International Journal of Psychological Research 11 (2), 77-85

  Artikel

  While popular within some cognitive science approaches, the embodiment approach has still found resistance, particularly in light of evidence arguing against strong forms of embodiment. Among other things, the embodiment approach breaks away from the Cartesian ontology of the modulatory system. We claim that the advantages of the embodiment approach are: a) it grounds cognition into modal experience, b) it is harmonious with a materialist philosophy of mind (emergent materialism), and c) it is supported by experimental research in various fields. However, embodiment must still address abstractions, theoretical misunderstandings (representations vs non-representations) and neuroscientific findings that challenge the extension and relevance of sensorimotor properties into cognitive processes. While the strong version of embodiment is seriously challenged by conceptual and physiological setbacks, its weak version is supported by compelling evidence. We suggest future research focus on the psychophysiological bases of grounded cognition and redirect efforts towards the field of cross-modal correspondence.

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• Embodied concept mapping Blending structure-mapping and embodiment theories

  2017. Fernando Marmolejo-Ramos (et al.). Pragmatics & Cognition 24 (2), 164-185

  Artikel

  Metaphors are cognitive and linguistic tools that allow reasoning. They enable the understanding of abstract domains via elements borrowed from concrete ones. The underlying mechanism in metaphorical mapping is the manipulation of concepts. This article proposes another view on what concepts are and their role in metaphor and reasoning. That is, based on current neuroscientific and behavioural evidence, it is argued that concepts are grounded in perceptual and motor experience with physical and social environments. This definition of concepts is then embedded in the Structure-Mapping Theory (SMT), a model for metaphorical processing and reasoning. The blended view of structure-mapping and embodied cognition offers an insight into the processes through which the target domain of a metaphor is embodied or realised in terms of its base domain. The implications of the proposed embodied SMT model are then discussed and future topics of investigation are outlined.

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• A Meta-Analysis of Odor Thresholds and Odor Identification in Autism Spectrum Disorders

  2017. Maria Larsson, Carlos Tirado, Stefan Wiens. Frontiers in Psychology 8

  Artikel

  Autism Spectrum Disorders (ASD) are often accompanied by atypical visual, auditory, and tactile sensory behavior. Evidence also suggests alterations of the olfactory system, but the pattern of findings appears mixed. To quantify this pattern systematically, we conducted a meta-analysis. Studies were included if they examined olfactory function (i.e., odor threshold, or odor identification) in ASD compared with healthy age-matched control groups. We also coded for the potential moderators gender, age, and IQ. Articles were identified through computerized literature search using Web of Science, PubMed, and Scopus databases. A total of 11 articles compared odor threshold and/or odor identification between cases and controls (for threshold, n = 143 ASD and 148 controls; and for identification, n = 132 ASD and 139 controls). Effects sizes showed a substantial heterogeneity. As a result, the 95% prediction intervals were wide and ranged between a large negative and a large positive effect size for odor threshold, [-1.86, 2.05], and for odor identification, [-1.51, 2.52]. Exploratory analyses suggested that age and IQ may be potential moderators. To conclude, the large heterogeneity is consistent with the notion of both hyposensitivity and hypersensitivity in individuals with ASD. However, future research needs to predict and test the specific direction of the effect to provide convincing evidence for atypical olfactory functions in ASD.

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