Some researchers believe that little children need to feel the beat on their bodies to develop beat-competency, and learn the "feel" of music with different time signatures.
Instruments may hinder this type of learning, providing an unnatural extension of children's bodies, and robbing them of the feel of the beat on their skin.
Of course, instruments are fun, and will probably always feature in children's music classes. This latest research just warns us not to overdo it, and not to underestimate the value of really feeling the beat.
We have always known that some instruments are more suited to early childhood than others. For example, triangles are just too difficult and quite unsatisfying for little ones.
I had always thought that maracas were great for kids because they were easy to grasp. At a workshop recently the conductor made an interesting point. When you shake a maraca, there is a lag between the movement you make and the noise of the beads inside catching up. It's actually quite tricky to keep the beat with this instrument. Of course they are enormous fun, but I won't be using them for early beat-keeping activities in my classes.
Percussion instruments are still fantastic for experiencing different timbre (tone quality) and encouraging children to experiment with sound and really listen. They are also a great motivational device. We just have to be careful how we use them.
