Infant and Child lab

INFANT AND CHILD STUDIES

In our studies we aim to find out how infants perceive their environment, and which factors influence their actions, thoughts, and feelings. For this purpose, we apply different methods. Besides classical behavioral observation methods, we also use various technical approaches. The following paragraphs give an overview of the different methods we employ.

• Behavioral studies

In our behavioral studies we observe different aspects of children’s behavior as reactions to information that we systematically provide them with. What counts as a reaction can vary enormously – we measure looking durations and grasping preferences, as well as choices, depending on the research topic and the age of the children we are studying. While it is easy to collect verbal responses from older children, this is impossible when studying infants. Therefore, we use methods specifically adapted to the abilities of young infants such as, for example, habituation and familiarization. Here, we take advantage of the fact that infants tend to look longer at unfamiliar objects or images. Accordingly, we familiarize infants to a specific object, face, or action across several trials, and measure their looking times to the respective display. As familiarization occurs, we can observe their looking times diminishing significantly. Then we present the infants with a novel object or image. To the extent that infants recognize the novelty of this object or image, we expect them to increase their looking time towards this novel exemplar. This way, we can find out which differences between objects or images infants can perceive and what they prefer to look at.

With older children and adults, we are able to instruct our participants to perform complex tasks and respond to specific questions. One common approach is the “two-alternate forced choice” task. In this task, participants can be asked a specific question about a visual stimulus such as a photograph, and have to choose one of two possible answers. For example, we would show participants a series of faces, and they would need to respond whether each face is showing a positive or a negative emotion.  Alternatively, participants can be asked to rate a stimulus on a scale, for example, if we were to ask participants to tell us how trustworthy a face appears on a scale of 1 (not very trustworthy) to 5 (very trustworthy). Another common approach are go/no-go tasks. Here, participants are asked to press a button only when they see a specific object out of a series of different objects. One example could be to show participants a series of differently colored shapes for several seconds at a time, and ask them to only press a button when they see a specific shape or color. We are typically interested in both the accuracy of participants in such tasks (i.e., how many times they responded correctly), as well as additional information such as the speed with which they gave correct responses. These two measures are extremely useful in measuring whether participants are biased in favor of particular responses, and whether they are more efficient in mentally processing specific types of stimuli.

• Studies employing the Vicon movement analysis system

Healthy adults grasp objects in a very characteristic and task-oriented way.  For example, they rotate their hand according to the orientation of an object and adjust their hand opening to an object’s size even before they have grasped the object. This indicates that most aspects of even the simplest actions are planned. In the context of different projects, we investigate the question whether children and even infants plan their actions in the same way as adults. Because movement adaptations connected to planning are often very slight and nearly invisible to the naked eye, we use a complex movement analysis system to record even the slightest body movements. This system is comprised of several infrared cameras that record the positions and movements of the body from different perspectives. It allows us to calculate, for example, how fast children move their hands and how joint angles change during a movement. In order to be able to record the movements, we attach small reflecting pellets with an adhesive tape to different body parts (e.g. the wrist). The infrared cameras can register the reflections of the pellets as they move, and use this information to reconstruct different motion paths.

• Studies on the detection of brain activity using electroencephalography (EEG)

EEG is the abbreviation for electroencephalography, from the Greek words enképhalos (english: brain) and gráphein (english: write). In simple terms, it allows us to measure electrical brain waves. This non-invasive method is especially helpful in developmental psychology for gaining knowledge about the specific function of the human brain. The main goal of our EEG studies is to contribute to the understanding of the brain’s physiological basis and the changes it undergoes during the development of perception and action. The recording of brain activity during our studies is done using electrodes (sensitive sensors for the derivation of the brain waves), which are attached to a cap worn by the participant.  After the adjustment of the cap, the participants can be, for example, presented with different pictures, and have to solve age-appropriate tasks. By connecting the EEG-data with observed behavior we can gain a better understanding of the neuronal basis of thinking and acting. Thanks to its harmless and non-invasive nature, EEG can be used for all age groups, even for newborns.

• Studies on the detection of eye movements using Eye-tracking

Our department possesses several eye-trackers, systems which use a computer display and infra-red cameras to track the position of a person’s pupils, and use that information to calculate where on the display the person is looking. These systems are extremely useful in experiments where participants need to either simply look at visual stimuli (e.g., photographs of faces), or respond to them in some way. Using an eye-tracker, we are able to measure where participants look on the screen while they perform these tasks, for how long they look at those areas, what order participants examine the different areas of the screen, and what kind of gaze behaviors our participants perform. Examples of gaze behaviors include fixations (focusing at a particular point), saccades (making eye movements from one area to another), or pursuits (following a moving object). Such measurements can give us a lot of useful information about how people process visual stimuli, such as which parts of an object are more important for identifying it, which objects are more visually attractive, in what order do participants visually encode images, etc.

• Mobile Eye-tracking

The use of a stationary eye tracker provides many opportunities to answer specific research questions. However, its usage is limited to studies in which the participant is in a resting position. An innovative advancement in eye tracking is the mobile eye tracker. The principles of its function are similar to the stationary eye tracking system, with infrared cameras tracking the position of a person’s pupils. However, the mobile eye tracking system also allows us to record the person’s eye movement during movement, which allows us to use more naturalistic study designs. In our department, we use a mobile eye tracker manufactured by Positive Science. This device is adjustable for the special needs of infants and toddlers. The eye tracker, which records the eye movements of the right eye, is attached to a soft headband. A second camera which records the baby’s surroundings, also known as a scene camera, is attached to the middle of the headband. Data from these sensors are transmitted to a computer, allowing us to observe the baby’s gaze behavior and analyze this data afterwards. Thanks to the small size and light weight of this eye tracker, there are no restrictions on baby’s movements. Using this system we can, for example, investigate infants’ gaze behavior when they explore an unfamiliar room.

• Studies on the detection of muscle activity using surface electromyography (EMG)

When we tense a muscle, small electrical impulses are sent back and forth between our brain and the muscle tissue. These electrical activities can be recorded using electromyography (EMG). This gives us information about when and to what extent different muscles are activated. In our department, we only use surface EMG, which involves attaching small electrodes to the skin. This simple procedure is similar to applying small band-aids and is entirely harmless. We use skin-friendly adhesive electrodes and clean the skin with alcohol pads before application so that the signals can be recorded without interference. For example, the EMG allows us to measure the activity of various facial muscles that are responsible for a smile or a frown. Changes in facial mimicry can be extremely subtle and invisible to the naked eye. This is the case, for example, when we look at another person - when they smile, our check muscles which are responsible for smiling are also active, but only so slightly that we don’t notice or see it. However, EMG can detect this low level of activity and gives us an insight into neurophysiological processes.

• Studies in our mobile research vehicle “Mobilab”

In addition to our numerous studies at our department, some studies take place in our mobile research vehicle "Mobilab". This gives us the opportunity to visit families at home, to make participation as easy and convenient as possible. For example, we have conducted studies on the motor development of children with congenital clubfoot, for which we visited families throughout Germany with our Mobilab.