Multisensory integration reduces landmark distortions for tactile but not visual targets.

Target localization is influenced by the presence of additionally presented nontargets, termed landmarks. In both the visual and tactile modality, these landmarks led to systematic distortions of target localizations often resulting in a shift toward the landmark. This shift has been attributed to averaging the spatial memory of both stimuli. Crucially, everyday experiences often rely on multiple modalities, and multisensory research suggests that inputs from different senses are optimally integrated, not averaged, for accurate perception, resulting in more reliable perception of cross-modal compared with uni-modal stimuli. As this could also lead to a reduced influence of the landmark, we wanted to test whether landmark distortions would be reduced when presented in a different modality or whether landmark distortions were unaffected by the modalities presented. In two experiments (each n = 30) tactile or visual targets were paired with tactile or visual landmarks. Experiment 1 showed that targets were less shifted toward landmarks from the different than the same modality, which was more pronounced for tactile than for visual targets. Experiment 2 aimed to replicate this pattern with increased visual uncertainty to rule out that smaller localization shifts of visual targets due to low uncertainty had led to the results. Still, landmark modality influenced localization shifts for tactile but not visual targets. The data pattern for tactile targets is not in line with memory averaging but seems to reflect the effects of multisensory integration, whereas visual targets were less prone to landmark distortions and do not appear to benefit from multisensory integration.NEW & NOTEWORTHY In the present study, we directly tested the predictions of two different accounts, namely, spatial memory averaging and multisensory integration, concerning the degree of landmark distortions of targets across modalities. We showed that landmark distortions were reduced across modalities compared to distortions within modalities, which is in line with multisensory integration. Crucially, this pattern was more pronounced for tactile than for visual targets.

Tactile Landmarks: the Relative Landmark Location Alters Spatial Distortions.

The influence of landmarks, that is, nearby non-target stimuli, on spatial perception has been shown in multiple ways. These include altered target localization variability near landmarks and systematic spatial distortions of target localizations. Previous studies have mostly been conducted in the visual modality using temporary, artificial landmarks or the tactile modality with persistent landmarks on the body. Thus, it is unclear whether both landmark types produce the same spatial distortions as they were never investigated in the same modality. Addressing this, we used a novel tactile setup to present temporary, artificial landmarks on the forearm and systematically manipulated their location to either be close to a persistent landmark (wrist or elbow) or in between both persistent landmarks at the middle of the forearm. Initial data (Exp. 1 and Exp. 2) suggested systematic differences of temporary landmarks based on their distance from the persistent landmark, possibly indicating different distortions of temporary and persistent landmarks. Subsequent control studies (Exp. 3 and Exp. 4) showed this effect was driven by the relative landmark location within the target distribution. Specifically, landmarks in the middle of the target distribution led to systematic distortions of target localizations toward the landmark, whereas landmarks at the side led to distortions away from the landmark for nearby targets, and toward the landmark with wider distances. Our results indicate that experimental results with temporary landmarks can be generalized to more natural settings with persistent landmarks, and further reveal that the relative landmark location leads to different effects of the pattern of spatial distortions.

Effect-less? Event-files are not terminated by distal action effects.

Event-files that bind features of stimuli, responses, and action effects figure prominently in contemporary views of action control. When a previous feature repeats, a previous event-file is retrieved and can influence current performance. It is unclear, however, what terminates an event-file. A tacit assumption is that registering the distal (e.g., visual or auditory) sensory consequences of an action (i.e., the "action effect") terminates the event-file, thereby making it available for retrieval. We tested three different action-effect conditions (no distal action effect, visual action effect, or auditory action effect) in the same stimulus-response (S-R) binding task and observed no modulation of S-R binding effects. Instead, there were comparably large binding effects in all conditions. This suggests that proximal (e.g., somatosensory, proprioceptive) action effects terminate event-files independent of distal (e.g., visual, auditory) action effects or that the role event-file termination plays for S-R binding effects needs to be corrected. We conclude that current views of action control require further specification.

The speed prior account: A new theory to explain multiple phenomena regarding dynamic information.

Our perception of moving stimuli is prone to systematic biases. Different biases, for example concerning the perceived speed, or spatial location, of a dynamic, moving stimulus, have consistently been reported in the literature. Different lines of experimental research, together with different theoretical explanations, have emerged analyzing and discussing these biases separately. In the present study, we propose a new theoretical account to unite various effects relating to dynamic/moving stimuli: The speed prior account. The perceived location of a stimulus is suggested to reflect the combination of the sensory input, which is associated with uncertainty, and a prior expectation concerning stimulus speed. Discrepancies between the prior speed expectation and the actual speed of a stimulus then result in a distortion of perceived stimulus speed, leading to the various perceptual biases that have been observed. In the present study, we demonstrate that this new theory can already account for robust data patterns currently unexplained in the literature, while we additionally directly test the predictions of the new speed prior account across four experiments. The influence of stimulus speed was manipulated in two visual as well as two tactile studies (all N = 30). The results reveal a clear data pattern, consistent with the speed prior account, as perceived onset and offset location reveal strong interdependencies. The implications and possible future questions for the perception of moving stimuli, in particular, and dynamic information, more generally, are discussed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).