Sensory and spatial development
Bendy bodies
Some of our studies used the MIRAGE illusion box to look into how what we see and feel might change how we know where our hands are and what shape they are.
In one game we asked children to keep their hands as still as possible while we actually made them move their hands to a new location. We did this by creating the illusion that their hands were moving slowly inwards when actually their hands were moving outwards. Children could see what they thought was their hand in one place when it was really in another, and we then asked them to tell us where there hand really was.
Last year we found that young children knew where their real hand was more than older children. This year, we also had children count their own heartbeats in their head while measuring their real heartbeat. The idea was that children who were more in tune with their own body signals (better at judging heartbeats) would also be better at feeling where their hand really was.
Another game used our finger stretching illusion.
With this, we show children a live video of their finger and then pull on their finger at the same time as making the finger in the video stretch out. The effect is usually a very strong feeling that the finger is really being stretched.
We use this game to work out if young and older children put sensory information about what they see and feel together in the same way.
Children answered questions about how the finger stretching felt, and we also asked them to make a judgement about how long their finger really was before and after stretching it.
We found that children felt like their finger had been stretched and they also judged their finger to be longer than it really was, but it did not matter how old the child was or whether they were a boy or a girl.
This tells us that children can put together information from vision and touch to make sense of their own body from a very early age.
Winston's special boxes
Winston’s special boxes involved two parts. First, children observed their hands through the MIRAGE illusion box. Through the MIRAGE box children sometimes saw their hands in the same place as their actual hands and sometimes they saw them in a different location. They were asked to give an estimate of the location of their hands, so we were able to assess whether children relied more on their vision or their body position to make this judgement.
In the second part, children were introduced to Winston the bear and his special box, which contained a toy. Winston was shown to be either picking up the box or looking inside it. We asked children whether Winston could know about the colour or the weight of the toy by performing these actions. Through children’s responses we were able to assess whether children have an understanding of the correct action required to learn about certain object properties. We are also interested to see whether the incorrect responses children gave show a bias for looking as a source of knowledge.
We are still in the process of analysing the data. Previous studies from our team suggest that, in the MIRAGE, adults rely on visual information more than information given by our other senses. The question here is whether this bias is driven by repeated experience with vision (often in combination with other senses). If this is the case, then we would expect to see very little or no bias for vision in younger children, but such bias may be in operation in older children. Our analysis will also tell us whether the biases on the two tasks may be driven by the same process.
Catch the alien's nose!
Brushing teeth, tying shoelaces, and catching a ball all seem effortless. However, children with difficulties in hand-eye coordination may take longer to learn these daily reaching, grasping, and manipulating movements. By studying movement in children with a wide range of skills, we can further our understanding of children who have difficulties with hand-eye coordination.
In the 'Catch the alien's nose' game, we asked children aged 8-12 to imagine they were astronauts, and their space mission was to catch the nose of the alien when it lights up.
Sometimes, just after they started to reach for the nose, the light would jump to another alien’s nose. We wanted to know how quickly the children could move their hand to catch the second alien nose.
After saving the world from this alien invasion, we then asked the children to fix their spaceship, which was exploring the children’s manual dexterity. In this second game, the children had to place small pegs in holes as quickly as they could, and assemble axles and wheels for their spaceship.
From these space-mission games, we hope to develop a measure of hand-eye co-ordination skill that can predict scores on standardized tests, which can then be used to screen for movement co-ordination disorders such as dyspraxia. For example, we have found so far that children’s ability to switch between the aliens' noses relates closely to their ability to throw and catch balls – one of the standard skills assessed by occupational therapists.
Is that my hand?
In this game we used the MIRAGE illusion box to investigate how children combine information from vision, touch and proprioception (the sense of where our body is in space). To understand the world around us we need to combine information from these senses.
For example, we integrate information from another person’s facial expression, body language, tone of voice and speech to understand what they are saying. Interestingly, children are less likely than adults to notice a delay between visual information (seeing a person’s lips moving) and auditory information (hearing that person speak). This suggests that sensory integration develops with age. In this game we found that younger children were also less likely to notice a delay between when they saw a pencil touch their hand (visual information) and when they felt the touch (tactile information).
We also changed where children saw their hand and found that older children were more aware of a mis-match between the seen location and the actual location of their hand. These results suggest that both visual-tactile integration and visual-proprioceptive integration matures with age.
Sensory signals
In everyday life we receive information to many senses at the same time. Sometimes this multisensory information can be distracting; for example, while trying to read in a busy classroom we might also have to ignore the sound of people talking.
In this game a set of friendly characters (the Minions) were heading on a secret mission, and they needed people with super senses to help them. Children had to say whether they could see or hear words hidden in noise. The words gradually got more difficult to see and hear until we found the minimum detectable level.
In order to explore the effects of multisensory distraction upon detection we sometimes presented irrelevant information to another sense. For example, while children were trying to see words the sound of people talking was played.
We wanted to explore whether presenting irrelevant information to another sense influenced the minimum level children could detect a target word, and also whether it influenced the amount of time taken to detect a target.
We found that distracting information did not influence the minimum level children could see/hear target words. However, interestingly there was a slight decrease in the time taken to detect targets when presented with 'distracting' information to another sense. This is a similar effect to what we have found in adults.
We think that this difference in response time might have been because the distractors actually alerted children to the presence of the word, allowing them to detect it faster. This is because unlike the ongoing noise we try and ignore while concentrating in everyday life, the distractors in this study were very brief and presented at the same time as the target. Our future research will aim to further explore the circumstances under which multisensory information may help or hinder behaviour with development.
Listen up
Children have greater difficulty listening in noise than adults. This may make it very difficult for them to learn in noisy classrooms.
To understand more how background noise affects learning, we asked children to listen to a story with lots of people talking in the background, and that they had to be 'silly word detectives'. Whenever they heard a silly word, they had to press a button as quickly as possible. We thought that children would find this game very tiring.
We expected that they would not detect many words, and if they did, they would be slow in noticing them. Children did miss lots of silly words, but to our surprise, they were faster at detecting them than when listening in quiet.
To understand what was going on, we then asked the children to play the same game, but this time half of the story was in quiet, and the other half was in noise. Once again, we found that children detected fewer silly words when it was noisy, but they were always faster than when it was quiet. We also found that children were worse at silly word detection when it became quiet after being noisy.
We think children automatically become more alert to cope with the difficulty of the noisy conditions, but the noise may have a bad effect on their learning.
Beat the noise
When audiologists fit hearing aids, they need to know how well a child is likely to understand what is said when it is noisy. This is very difficult to work out, because children vary in their ability to use language to guess words they cannot hear clearly.
To help audiologists in their work, we recently developed pairs of sentences for use in the clinic which both ended in the same word. In one sentence, this final word could be guessed from the preceding context, while in the other sentence it could not. By combining the scores from these two sentence types, the audiologist can work out how well a child can hear, and also how well they can use language to guess what is difficult to hear.
At Summer Scientist Week, we asked children to listen to the sentence pairs in different kinds of noise and say what they heard. Children get better at this game as they get older, and we wanted to work out what is normal for children of different ages.
Using the scores that each child got for the game, we have now worked out what is the right amount of noise to use so that the game is equally difficult for all children. As part of this, we also found out that children prefer to rely on their hearing not their language to help them play the game.
Houston, we have a problem!
In our game the children piloted a spaceship lost in deep, dark space trying to find their friends. By deciding if specific sound properties from two spaceships were the same or different, children were able to send fireworks up to show their friends where they were, or to blow up aliens. We varied two properties of the spaceship sounds – the ear they were played in, and the pitch of the sounds. Throughout the game we measured if the children were faster at deciding that the sounds were different when both properties changed, compared to if just one property changed.
We are currently analyzing the results and expect to find that older children (aged 7 plus) are faster to decide that the sounds are different when both properties change, as adults do. In contrast we expect to find younger children to be equally fast in their decision making when one or both sound properties changed. This effect happens in vision, where younger children tend to focus on a single property of an object rather than objects as a whole.
Map it!
When we move through an environment to reach a destination, we often do so by using different parts of the environment as reference points - we call these landmarks. Some landmarks are more useful than others: a distinctive feature in the environment located at a point in our journey where a change in direction occurs (a turn) is likely to help us remember that turn more easily for future journeys, compared to a turn at a point in space where no distinctive feature can be found. We refer to the first type of landmark as a 'decision-point' or 'salient landmark'.
In our experiment, children watched short clips portraying first-person views of journeys through an environment. This environment contained landmarks located both at turns and at less salient locations.
After watching each video, the children saw a series of objects, and had to decide whether they had seen them in the video or not. These objects had appeared both at important and unimportant locations along the route.
By measuring both their accuracy and how quickly they responded, we are hoping to determine how the ability to take advantage of salient landmarks develops with age.
Although we are still working on the data, it seems that children of all ages were just as likely to correctly remember an important landmark as they were a less important one. They also didn’t seem to respond more quickly to important landmarks compared to less important ones, but older children were generally faster than younger ones.
After this, children were given a map bearing the layout of the environment without any landmarks.
Their job was to draw the route they had watched in the corresponding video from the start of the maze to the red room in question.
The goal of this part of the study was to find out how effectively children can transform their memory of a first-person view of a route into a trace of that path on a map.
We measured how likely children were to remember the right direction to turn at the first and at the second junction in the route.
We found that children of all ages were more likely to correctly remember which way to turn at the first junction than the second junction, but this difference was a lot smaller for the older children. By the age of 12, children were almost as good at remembering which way to turn at the second junction as they were at the first one.
The Racing Car Game
For this game we developed a new car racing game that was designed to investigate motor learning ability. In the game, children were asked to race a car towards a stop flag as quickly as they could using a computer mouse to steer the car. Sometimes the car pulled toward the right or left. We measured how well the children could adapt their steering to compensate for the change.
To begin with the children showed large steering errors, but with practice steering improved. Older children did better than the younger children, but even young children could perform the task fairly well and improved with practice. The current study confirmed that the task is suitable to test motor adaptation ability in children.