Training pet dogs for eye-tracking and awake fMRI

Abstract

In recent years, two well-developed methods of studying mental processes in humans have been successively applied to dogs. First, eye-tracking has been used to study visual cognition without distraction in unrestrained dogs. Second, noninvasive functional magnetic resonance imaging (fMRI) has been used for assessing the brain functions of dogs in vivo. Both methods, however, require dogs to sit, stand, or lie motionless while yet remaining attentive for several minutes, during which time their brain activity and eye movements are measured. Whereas eye-tracking in dogs is performed in a quiet and, apart from the experimental stimuli, nonstimulating and highly controlled environment, MRI scanning can only be performed in a very noisy and spatially restraining MRI scanner, in which dogs need to feel relaxed and stay motionless in order to study their brain and cognition with high precision. Here we describe in detail a training regime that is perfectly suited to train dogs in the required skills, with a high success probability and while keeping to the highest ethical standards of animal welfare-that is, without using aversive training methods or any other compromises to the dog's well-being for both methods. By reporting data from 41 dogs that successfully participated in eye-tracking training and 24 dogs IN fMRI training, we provide robust qualitative and quantitative evidence for the quality and efficiency of our training methods. By documenting and validating our training approach here, we aim to inspire others to use our methods to apply eye-tracking or fMRI for their investigations of canine behavior and cognition. Keywords Domestic dog. Eye-tracking. Functional magnetic resonance imaging. Positive reinforcement. Dog training After primates (see, e.g., Tomasello & Call, 1997), rodents (Pineno, 2010), corvids and parrots (ten Cate & Healy, 2017), and cetaceans (Mann, 2018), canines have become the main model system for the investigation of cognitive behavior in nonhuman animals (see, e.g., Katz & Huber, 2018; Miklósi, 2014). From a scientific point of view, dogs have become particularly attractive because of the interesting but yet not well understood interplay of long-term (canine

Exploring the dog–human relationship by combining fMRI, eye-tracking and behavioural measures

“…By conducting only few test trials (4 trials per experiment including stimuli repetition to counterbalance the sides), we tried to avoid strong habituation effects. From previous eye-tracking studies 42,108 in our lab we know that such habituation effects are also relevant for this kind of experiments. During the fMRI scans we tried to balance the amount of necessary stimuli repetitions and the exhausting duration of the scans for the dogs lying motionless in the scanner (two runs of ca.…”

Perception of dynamic facial expressions of emotion between dogs and humans

“…The testing protocol could also be further improved. In this study, we recorded naturalistic and spontaneous face-viewing behaviour in dogs without specific pre-experiment training (e.g., without shaping, clicker training and other associative techniques before the start of the experiment, as opposed to for example in Karl et al 2019) or any specific fixation on stimuli training; we used only luring (sensu Alexander et al 2011;Wallis et al 2017) to focus the dog's attention on a treat, to, for example, guide the dog into position and attend to the drift points on the screen, but not to create an association between task and reward. This methodological choice is important, because we aimed at studying naturalistic emotional responses in dogs, which might be impacted if extensive and/or intensive training is used before the experiment.…”

“…This methodological choice is important, because we aimed at studying naturalistic emotional responses in dogs, which might be impacted if extensive and/or intensive training is used before the experiment. While we did not reinforce sustained attention, we used treats or toys for luring the individuals throughout the protocol, which might not be appropriate for all research questions (e.g., fMRI studies, Karl et al 2019). Furthermore, we used a protocol that allowed small head/body movements from unrestrained dog participants that were not physically manipulated or mechanically forced into a particular position, which leads to more spontaneous responses.…”

“…Nonetheless, in general, dogs tend to look more towards negative dog faces than positive human faces (Somppi et al 2016). The mixed results from these previous studies might stem from methodological issues, such as the use of static and posed facial expressions that have not been validated in terms of their content (e.g., AUs), and the use of dogs trained to stand still and to look at the screen (i.e., trained using shaping and clicker training techniques over an average of 15 sessions lasting 30-45 min each, as described in for example Karl et al 2019) which might interfere with natural perceptual processes that require free head movements (Collewijn et al 1992).…”

“…Therefore, in the current study, we developed and applied a novel approach to compare human and dog perception of facial expressions: we eye-tracked participants allowing for free head (and body) movements, as they observed dynamic, spontaneous facial expressions validated by coding with human FACS and Dog-FACS (Waller et al 2013). We opted to use an eye-tracking protocol that allowed fully unrestrained (i.e., the dogs were not physically manipulated or mechanically forced, sensu Alexander et al 2011), and without specific pre-experiment fixation training (i.e., no shaping, capturing, clicker training nor any other association techniques were used to teach dogs before our experiment; for an alternative option of using an eye-tracker protocol that includes pre-training, please see Karl et al 2019), Instead, we only used luring (i.e., a food treat is used to guide the dog into a desired position or behaviour), which focus the dog's attention on the treat, but importantly, does not create an association between reward and task (Alexander et al 2011;Wallis et al 2017).…”