An increased interest of animal-assisted interventions (AAI) can be observed within clinical practice, even though it is still not entirely clear how the presence of an animal contributes to the outcome of a treatment. One theory maintains that the mere presence of an animal influences the therapeutic alliance between therapist and client.

However, results from a recent study suggest that a relationship between patient and health-provider alone is not sufficient to influence treatment outcomes, but that a therapeutic rationale is needed and that verbal instructions and suggestions are highly important in shaping participants' treatment expectations.

To investigate this theory, this study will combine AAI with a placebo intervention, as placebo interventions offer the basic form of intervention working through relationship and expectancy.

The effects of the presence of a dog will be assessed with a standardized experimental heat pain paradigm (TSA-II) in a randomized controlled trial in healthy participants (N=128).

After a baseline measurements of heat pain threshold and tolerance, participants will be randomly assigned to one of the following four conditions: a) placebo intervention , no dog present, b) placebo intervention, dog present, c) no placebo intervention, no dog present and d) no placebo intervention, dog present.

The dog will be introduced after randomization. Expectancy will be induced by telling participants that the contact to an animal increases the oxytocin level, which has an non inflammatory effect.

The placebo intervention will be a deceptive cream which is said to helps against pain.

Afterwards, posttreatment measurements will be conducted and participants fill in questionnaires about their perceptions of the experimenter.

A growing body of literature suggests that animal-assisted interventions (AAI) have important clinical effects on humans, e.g. decreased physiological stress, reduction of depression and anxiety symptoms and reduction in pain perception and experience. Such evidence leads to an increased interest in using AAI in clinical practice. However, it is still not quite clear how AAI works or in other words what it is that makes AAI effective. Therefore, it is crucial to investigate how the inclusion of animals in clinical practice contributes to beneficial therapeutic outcomes.

In this regard, it has been assumed that the presence of an animal enhances the development of the therapeutic alliance, which, in turn, has been shown to play a crucial role in the outcome of the treatment.

However, results from a recent study suggest that a relationship between patient and health-provider alone is not sufficient to influence treatment outcomes, but that a therapeutic rationale is needed and that verbal instructions and suggestions are highly important in shaping participants' treatment expectations.

As placebo effects are related to therapeutic rationale and relationship, the investigators would like to use an expectancy-induced placebo intervention to identify if animal-assisted intervention also works through these two components.

Given that placebo analgesia works well through therapeutic rationale the investigators decided to employ an animal-integrated placebo intervention study with healthy participants (N=128) in a standardized experimental heat pain paradigm. Even though a growing body of evidence highlights the positive effects of animal-assisted interventions until this day little is known about the mechanisms. There exist various hypotheses trying to explain why AAI works, most focusing on the crucial role of the animal in the intervention. However, to the best of the investigator's knowledge there has been no study which examined if the effectiveness of animal-assisted interventions could simply be explained by the power of the therapeutic rational and the relationship. Therefore, it is still unknown if AAI is effective because of the animal or because of its influence on the therapeutic relationship and the given therapeutic rationale.

It is important to understand how AAI works. Moreover, if AAI, like other interventions, is about expectation and relationship, this could have important implications for clinical practice and a better understanding of how AAI must be used to be effective.

If AAI works through similar mechanisms as the placebo, then both interventions should have a similar impact on the outcome of the intervention (reduced pain perception, increased placebo analgesia). Findings of this study could have important implications, not only for clinical practice of AAI but also for intervention in general as the results could help to better understand the importance of these two components.

Inclusion Criteria:

• Age ≥ 18 years
• Right-handedness

Exclusion Criteria:

• Being scared of dogs by self-report
• dog hair allergy by self-report
• Any acute or chronic disease (chronic pain, hypertension, heart disease, renal disease, liver disease, diabetes) as well as skin pathologies, neuropathies or nerve entrapment symptoms, sensory abnormalities affecting the tactile or thermal modality
• Pregnancy
• Current medications (psychoactive medication, narcotics, intake of analgesics) or being currently in psychological or psychiatric treatment
• Insufficient German language skills to understand the instructions
• Previous participation in studies using pain assessment with Peltier Devices
• Current or regular drug consumption (THC, cocaine, heroin, etc.)

The investigators are planning on sharing the anonymized data on an openly assess platform.

As the employed study design necessitates the deception of participants about the true nature of the used intervention, i.e. placebo cream and the true aim of the dog's presence.

After the termination of the study, all the subjects are debriefed regarding the real experimental procedures.