[The others and I: How social interactions change the perception of other persons. The Cyberball paradigm and its indications in the migration context]. / Die anderen und ich: Wie soziale Interaktionen die Wahrnehmung des anderen verändern. Das Cyberball-Paradigma und seine Indikationen im Migrationskontext.

What effect does social exclusion have on the perception of the other person and how can this effect be recorded with the help of experimental methods? Answering this question can provide psychologists, sociologists and clinicians with valuable insights for understanding as well as for concrete interaction with the people or groups concerned. Social groups that are particularly frequently confronted with social exclusion include people with mental illness, migrants and ethnic minorities. In this article we present the results of an experimental preliminary study on healthy volunteers in which we used a modified version of the cyberball paradigm to investigate the effects of social exclusion on the spontaneous assessment of personality traits such as attractiveness, trustworthiness, aggressiveness and dominance. The results of our study show that these effects can be quantified with the help of the cyberball paradigm and that the perception of the other person changes after a relatively short period of social interaction depending on their valence. Against the background of these findings, we discuss the potential of this paradigm to investigate social factors that can play a role in the development of mental illness in migrants and discuss the particularities to be considered in prospective application in the risk groups mentioned above.

Setting things straight: A comparison of measures of saccade trajectory deviation.

In eye movements, saccade trajectory deviation has often been used as a physiological operationalization of visual attention, distraction, or the visual system's prioritization of different sources of information. However, there are many ways to measure saccade trajectories and to quantify their deviation. This may lead to noncomparable results and poses the problem of choosing a method that will maximize statistical power. Using data from existing studies and from our own experiments, we used principal components analysis to carry out a systematic quantification of the relationships among eight different measures of saccade trajectory deviation and their power to detect the effects of experimental manipulations, as measured by standardized effect size. We concluded that (1) the saccade deviation measure is a good default measure of saccade trajectory deviation, because it is somewhat correlated with all other measures and shows relatively high effect sizes for two well-known experimental effects; (2) more generally, measures made relative to the position of the saccade target are more powerful; and (3) measures of deviation based on the early part of the saccade are made more stable when they are based on data from an eyetracker with a high sampling rate. Our recommendations may be of use to future eye movement researchers seeking to optimize the designs of their studies.

Accessory stimuli speed reaction times and reduce distraction in a target-distractor task.

Eye movements in a visual search task are drawn towards items irrelevant to the search (distractors). Advance information about the position or features of distractors can reduce this effect, by speeding the resolution of conflict between search target and distractor. The present study investigated whether this can also be achieved by a prime that merely warns of an impending task without providing any other information (an accessory stimulus). We found that accessory stimuli speed the initiation of a saccade to the target, but also speed the resolution of target-distractor conflict. This finding suggests that the oculomotor system can be prepared to counteract distraction in advance of task onset, without requiring information about a specific spatial location or feature.

The CB1 Neutral Antagonist Tetrahydrocannabivarin Reduces Default Mode Network and Increases Executive Control Network Resting State Functional Connectivity in Healthy Volunteers.

BACKGROUND: The cannabinoid cannabinoid type 1 (CB1) neutral antagonist tetrahydrocannabivarin (THCv) has been suggested as a possible treatment for obesity, but without the depressogenic side-effects of inverse antagonists such as Rimonabant. However, how THCv might affect the resting state functional connectivity of the human brain is as yet unknown. METHOD: We examined the effects of a single 10mg oral dose of THCv and placebo in 20 healthy volunteers in a randomized, within-subject, double-blind design. Using resting state functional magnetic resonance imaging and seed-based connectivity analyses, we selected the amygdala, insula, orbitofrontal cortex, and dorsal medial prefrontal cortex (dmPFC) as regions of interest. Mood and subjective experience were also measured before and after drug administration using self-report scales. RESULTS: Our results revealed, as expected, no significant differences in the subjective experience with a single dose of THCv. However, we found reduced resting state functional connectivity between the amygdala seed region and the default mode network and increased resting state functional connectivity between the amygdala seed region and the dorsal anterior cingulate cortex and between the dmPFC seed region and the inferior frontal gyrus/medial frontal gyrus. We also found a positive correlation under placebo for the amygdala-precuneus connectivity with the body mass index, although this correlation was not apparent under THCv. CONCLUSION: Our findings are the first to show that treatment with the CB1 neutral antagonist THCv decreases resting state functional connectivity in the default mode network and increases connectivity in the cognitive control network and dorsal visual stream network. This effect profile suggests possible therapeutic activity of THCv for obesity, where functional connectivity has been found to be altered in these regions.

Neural effects of cannabinoid CB1 neutral antagonist tetrahydrocannabivarin on food reward and aversion in healthy volunteers.

BACKGROUND: Disturbances in the regulation of reward and aversion in the brain may underlie disorders such as obesity and eating disorders. We previously showed that the cannabis receptor subtype (CB1) inverse agonist rimonabant, an antiobesity drug withdrawn due to depressogenic side effects, diminished neural reward responses yet increased aversive responses (Horder et al., 2010). Unlike rimonabant, tetrahydrocannabivarin is a neutral CB1 receptor antagonist (Pertwee, 2005) and may therefore produce different modulations of the neural reward system. We hypothesized that tetrahydrocannabivarin would, unlike rimonabant, leave intact neural reward responses but augment aversive responses. METHODS: We used a within-subject, double-blind design. Twenty healthy volunteers received a single dose of tetrahydrocannabivarin (10mg) and placebo in randomized order on 2 separate occasions. We measured the neural response to rewarding (sight and/or flavor of chocolate) and aversive stimuli (picture of moldy strawberries and/or a less pleasant strawberry taste) using functional magnetic resonance imaging. Volunteers rated pleasantness, intensity, and wanting for each stimulus. RESULTS: There were no significant differences between groups in subjective ratings. However, tetrahydrocannabivarin increased responses to chocolate stimuli in the midbrain, anterior cingulate cortex, caudate, and putamen. Tetrahydrocannabivarin also increased responses to aversive stimuli in the amygdala, insula, mid orbitofrontal cortex, caudate, and putamen. CONCLUSIONS: Our findings are the first to show that treatment with the CB1 neutral antagonist tetrahydrocannabivarin increases neural responding to rewarding and aversive stimuli. This effect profile suggests therapeutic activity in obesity, perhaps with a lowered risk of depressive side effects.

Saccadic eye movements in dual tasking: No impairment of spatial planning, but delayed execution of saccades.

In the target-distractor saccade task, a target and an irrelevant distractor are simultaneously presented and the task itself consists of a target-directed saccade. Findings usually show that as saccade latency increases, saccade trajectory deviation towards the distractor decreases. We presented this saccade task in two dual-task experiments to address the open question of whether performance of an auditory-manual task simply delays the temporal execution of a saccade, or whether it also interferes with the spatial planning of the saccade trajectory. We measured saccade latency, as a measure of a delay in execution, and saccade trajectory deviation, as a measure of the spatial planning. In Experiment 1, the auditory-manual task was a two-choice reaction time (two-CRT) task, and in Experiment 2, it was a go-no-go task. Performing the two tasks in close temporal succession shortly delayed the temporal execution of the saccade, but did not influence the spatial planning of the saccade trajectory. This result pattern was more pronounced when the auditory-manual task required the selection and execution of one of two possible manual responses (Experiment 1), less pronounced when the auditory-manual task required the decision to execute a button press (go condition, Experiment 2), and absent when the auditory-manual task required the decision to inhibit a button press (no-go condition, Experiment 2). Taken together, the manual response rather than the response selection process of the auditory-manual task led to a delay of saccade execution, but not to an impairment of the spatial planning of the saccade trajectory.

Expectations and perceptual priming in a visual search task: Evidence from eye movements and behavior.

An extensive amount of research indicates that repeating target and distractor features facilitates pop-out search while switching these features slows the search. Following the seminal study by Maljkovic and Nakayama (1994), this "priming of pop-out" effect (PoP) has been widely described as an automatic bottom-up process that is independent of the observers' expectations. At the same time, numerous studies highlight the crucial role of expectations in visual attention deployment. Our experiment shows that in contrast to previous claims, PoP in a classic color singleton search task is a mix of automatic processing and expectations. Participants searched for a uniquely colored diamond among 2 same-colored distractors. Target color sequences were either predictable (e.g., 2 red-target-green-distractors trials, followed by 2 green-target-red-distractors trials, and so on) or random. Responses were faster in predictable color sequences than randomly changing ones with equal number of repetitions of target colors on preceding trials. Analyses of observers' eye movements showed that predictability of target color affected both latency and accuracy of the first saccade during a search trial. Our results support the idea that PoP is governed not only by automatic effects from previous target or distractor features but also by top-down expectations. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Salience from multiple feature contrast: Evidence from saccade trajectories.

We used eye tracking to quantify the extent to which combinations of salient contrasts (orientation, luminance, and movement) influence a central salience map that guides eye movements. We found that luminance combined additively with orientation and movement, suggesting that the salience system processes luminance somewhat independently of the two other features. On the other hand, orientation and movement together influenced salience underadditively, suggesting that these two features are processed nonindependently. This pattern of results suggests that the visual system does not sum sources of salience linearly, but treats some sources of salience as redundant.

Neural mechanisms of eye contact when listening to another person talking.

Eye contact occurs frequently and voluntarily during face-to-face verbal communication. However, the neural mechanisms underlying eye contact when it is accompanied by spoken language remain unexplored to date. Here we used a novel approach, fixation-based event-related functional magnetic resonance imaging (fMRI), to simulate the listener making eye contact with a speaker during verbal communication. Participants' eye movements and fMRI data were recorded simultaneously while they were freely viewing a pre-recorded speaker talking. The eye tracking data were then used to define events for the fMRI analyses. The results showed that eye contact in contrast to mouth fixation involved visual cortical areas (cuneus, calcarine sulcus), brain regions related to theory of mind/intentionality processing (temporoparietal junction, posterior superior temporal sulcus, medial prefrontal cortex) and the dorsolateral prefrontal cortex. In addition, increased effective connectivity was found between these regions for eye contact in contrast to mouth fixations. The results provide first evidence for neural mechanisms underlying eye contact when watching and listening to another person talking. The network we found might be well suited for processing the intentions of communication partners during eye contact in verbal communication.