Avoiding meal distractions

My father is 80 years old and has Alzheimer's. Still has fine motor autonomy (eg, use cutlery). However, any physical detail what can confuse and disrupt, causing him to give up what he can still do for you. All the dishes we use at home have drawings of flowers and colored small branches around the rim (my mom likes bright colors, everywhere). Three months ago I noticed that he was trying to pick up food on the rim of the dish, rather than at its center and spent much time on this "quest", eventually got bored and gave up eating. So I bought completely white dishes, and since that time, he began to eat by himself. I am completely convinced that it is essential to reduce the noise to their sensations and perceptions, so it does not lose its attention you want to do. Thank you.