Ivan makarov
@hi.is
Faculty of Industrial Engineering, Mechanical Engineering and Computer Science; Icelandic Vision Lab, Faculty of Psychology, School of Health Sciences
University of Iceland
RESEARCH INTERESTS
visual attention, visual perception, tactile attention, multimodal attention
Scopus Publications
Scholar Citations
Scholar h-index
Scopus Publications
Ivan Makarov, Runar Unnthorsson, Árni Kristjánsson, and Ian M. Thornton
Springer Science and Business Media LLC
Ivan Makarov, Snorri Steinn Stefánsson Thors, Elvar Atli Ævarsson, Finnur Kári Pind Jörgensson, Nashmin Yeganeh, Árni Kristjánsson, and Runar Unnthorsson
Association for Computing Machinery (ACM)
When two brief vibrotactile stimulations are sequentially applied to observers’ lower back, there is systematic mislocalization of the stimulation: if the second stimulation is of higher intensity than the first one, observers tend to respond that the second stimulation was above the first one, and vice versa when weak intensity stimulation follows a strong one. This haptic mislocalization effect has been called the intensity order illusion . In the original demonstration of the illusion, frequency and amplitude of the stimulation were inextricably linked so that changes in amplitude also resulted in changes in frequency. It is therefore unknown whether the illusion is caused by changes in frequency, amplitude or both. To test this, we performed a multifactorial experiment, where we used L5 actuators that allow independent manipulation of frequency and amplitude. This approach enabled us to investigate the effects of stimulus amplitude, frequency and location, and to assess any potential interactions among these factors. We report four main findings: (1) we were able to replicate the intensity order illusion with the L5 tactors; (2) the illusion mainly occurred in the upwards direction, or in other words, when strong stimulation following a weaker one occurred above or in the same location as the first stimulation; (3) the illusion did not occur when similar stimulation patterns were applied in the horizontal direction; and (4) the illusion was solely due to changes in amplitude, whereas changes in frequency (100 Hz vs 200 Hz) had no effect.
Nashmin Yeganeh, Ivan Makarov, Runar Unnthorsson, and Árni Kristjánsson
MDPI AG
What are the effects of frequency variation of vibrotactile stimuli on localization acuity? The precise localization of vibrotactile stimuli is crucial for applications that are aimed at conveying vibrotactile information. In order to evaluate the ability to distinguish between vibrotactile stimuli based on their frequency and location on the forearm, we used a relative point localization method. Participants were presented with pairs of sequential vibrotactile stimuli at three possible locations on the forearm and asked to determine whether the second stimulation occurred at the same location as the first one in the pair or not. The stimulation frequency varied between 100 Hz, 150 Hz, 200 Hz and 250 Hz, which covers the range of frequencies that human observers are most sensitive to. The amplitude was kept constant. Our results revealed that the ability to discriminate between actuators remained unaffected by variations in the frequency of vibrotactile stimulation within the tested frequency range. The accuracy of the tactile discrimination task was heavily dependent on the location of the stimulation on the forearm, with the highest accuracy close to the wrist and elbow, locations that may serve as tactile anchor points. Our results highlight the critical role of stimulation location in precise vibrotactile localization and the importance of careful consideration of location in the design of forearm-mounted vibrotactile devices.
Nashmin Yeganeh, Ivan Makarov, Árni Kristjánsson, and Runar Unnthorsson
American Society of Mechanical Engineers
Abstract This paper reports on an empirical study that investigated the effect of frequency on the acuity of spatial localization on the skin of the forearm, as well as differences in localizability at different locations on the forearm. Three actuators were positioned in a 3 × 1 array along the forearm, and two adjacent actuators were sequentially activated with a 100 ms interstimulus interval, followed by activation of one of the three actuators in random order. Participants were asked about the direction of the second stimulation relative to the first one, and whether it was perceived in the same location as the first, below, or above it. Three frequencies — 100Hz, 200Hz, and 250Hz — were used for the stimuli. Results show that the frequency of the stimulus has a negligible influence on accuracy when the amplitude is kept constant. However, significant differences in the localization accuracy were found at different parts of the forearm. This study provides valuable insights into the design of tactile displays for conveying information on the skin. It suggests that spatial resolution may be optimized by positioning the actuators appropriately, rather than by manipulating the frequency of the stimulus.
F.A. Sapronov, I.M. Makarov, and E.S. Gorbunova
Moscow State University of Psychology and Education
<p>Categorization is the process by which objects are combined according to a certain principle, which provides more efficient and cost-effective information processing. One of the topical areas of research in this field is the study of the categorical effect in perceptual tasks, for example in the task visual search task. The present study investigated the effect of the role of category (basic or superordinate) on the time of guidance - the search for a target stimulus and verification - the time of identification of a target stimulus in a hybrid search task. Subjects had to find certain objects on the screen, which could be specified either as basic-level categories (e.g., cars) or superordinate-level categories (e.g., transport vehicles). An eye-tracking method was used to separate the entire hybrid search process into a guidance and a verification. A significant effect of category level was found on the rate of guidance, but not on the rate of verification.</p>
Nashmin Yeganeh, Ivan Makarov, Snorri Steinn Stefánsson Thors, Árni Kristjánsson, and Runar Unnthorsson
MDPI AG
While vibrotactile stimulation shows promise for sensory substitution devices, a crucial question concerns vibrotactile spatial resolution. We examined the optimum distance between three voice coil actuators (model: lofeltL5) on the forearm. Three actuators were embedded in a fabric-based vibrotactile sleeve where the actuators were placed in enclosures 3D-printed on the fabric. We used the relative point localization method where observers must discriminate whether two successive stimulations are in the same location or not. The resolution was measured for five vibrotactile sleeves, each with different distances between the actuators on the longitudinal axis of the forearm. The various distances were tested in a random order. In experiment one, pairs of stimuli were delivered sequentially in a random order to two adjacent actuators of the tactile sleeve on the upper side of the forearm. The task was to identify the perceived direction of the second stimulation (up, down, or the same) relative to the first one. Experiment two involved the same procedure but for the underside of the forearm. Taking the restrictions of the physical dimensions of the forearm and the design considerations into account, our results suggest that 20 mm is the optimum distance between the voice coil actuators (Model: Lofelt L5) for successful discrimination with high accuracy between the two stimulus locations on the forearm. There were no significant differences between the upper and undersides of the forearm.
Nashmin Yeganeh, Ivan Makarov, Snorri Steinn Stefánsson Thors, Hafliði Ásgeirsson, Árni Kristjánsson, and Rúnar Unnþórsson
American Society of Mechanical Engineers
Abstract This study presents a new design of a wearable vibrotactile device — a tactile sleeve consisting of three voice coil actuators (Model: Lofelt L5). The device was made within an R&D project aimed at developing a wearable for enhancing the music perception of cochlear implant recipients. The aim is to provide tactile stimulation in addition to the cochlear implant stimulation — generating an audio-tactile music experience. We also present the results of an experiment performed to investigate whether the sleeve can be used to identify songs from tactile stimulation and investigate the effects of different encodings. Five short music segments were used, and the tactile stimulation provided by each voice coil actuator conveyed song information (Bass or drum). Participants had intact hearing. At the beginning of the experiment, the participants listened to one song via headphones. Afterward, they were presented with various tactile encodings of the songs in random order. Their task was to identify the encoding of the song that was played. In this experiment, an investigation of the best combination of information from the bass versus drums was conducted. The results confirm that the sleeve can provide tactile stimulation that can be used to identify songs without audio. The results also provide insights into which encodings are most useful for conveying music.
Ivan M. Makarov and Elena S. Gorbunova
Frontiers Media SA
Three experiments investigated the role of target-target perceptual similarity within the attentional blink (AB). Various geometric shapes were presented in a rapid serial visual presentation task. Targets could have 2, 1, or 0 shared features. Features included shape and size. The second target was presented after five or six different lags after the first target. The task was to detect both targets on each trial. Second-target report accuracy was increased by target-target similarity. This modulation was observed more for mixed-trial design as compared with blocked design. Results are discussed in terms of increased stability of working memory representations and reduced interference for second-target processing.
Elena S. Gorbunova, Kirill S. Kozlov, Sofia Tkhan Tin Le, and Ivan M. Makarov
Frontiers Media SA
Visual search (VS) for multiple targets is especially error prone. One of these errors is called subsequent search misses (SSM) and represents a decrease in accuracy at detecting a second target after a first target has been found. One of the possible explanations of SSM errors is working memory (WM) resource depletion. Three experiments investigated the role of WM in SSM errors using a dual task paradigm. The first experiment investigated the role of object WM using a classical color change detection task. In the second and the third experiments, a modified change detection task was applied, using shape as the relevant feature. The results of our study revealed no effect of additional WM task on second target detection in dual-target VS. To this end, SSM errors are not related to WM resource depletion. On the contrary, WM task performance was violated by dual-target VS as compared to single-target VS, when the targets in VS task were defined by the same feature used in the WM task.