objects ? is achieved largely by the workings of the eye itself. Perception is achieved by the occipital and parietal lobes, with information about colour, shape and movement being processed separately by the occipital cortex before it is passed on to the parietal lobe for combination into a complete 3D picture of the world. This means that someone with dementia could have difficulty seeing what an object is, despite both eyes being in perfect condition. However, it is still necessary to maximise their eyesight (for example, with correct prescription spectacles) so that the brain has as much information to work with as possible. For more information, see Factsheet 527, Visuoperceptual difficulties in dementia . The parietal lobe The functions of the parietal lobe are somewhat more diverse, and there is a significant difference between the dominant and non-dominant sides. The dominant parietal lobe (usually the left half) can be thought of as being concerned with things we have to put together into an order or structure. So tasks such as reading and writing, which require putting letters and words together, and calculation, which involves ordering and combining numbers, are critically dependent on the dominant parietal lobe. This side of the parietal lobe has also been heavily implicated in a condition known as apraxia (an impairment of learned purposive movements). 'Dressing apraxia' is the form of apraxia most commonly noticed in people with Alzheimer's disease, and reflects not only a lack of co-ordination but an actual forgetting of the movements required