Misperceptions and misidentifications, and dementia

A person with dementia may mistake objects or people for things they are not. Misperceptions and misidentifications can be caused by problem with a person's eyes, or by problems with the brain. Find out how to support a person who is experiencing this. 

Sight, perception and hallucinations in dementia
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What are misperceptions and misidentifications?

The most common type of misperceptions and misidentifications are visual. They are caused by damage to the eyes, or by problems with another part of the visual system and the brain. For some people they are caused by both.

Misperceptions happen when the person sees one thing as something else. For example, mistaking blue floor tiles for water.

Misidentifications happen when the person has problems identifying specific objects and people. For example, mistaking their son for their husband.

Some mistakes could be caused by either, for example someone may mistake their television remote for their mobile phone because:

  • their visual system is damaged, and it’s not clearly seen (misperceived) as a television remote
  • or, it might be clearly seen as a television remote but damage in the brain causes it to be incorrectly understood (misidentified) as a mobile phone.

A person with dementia may also have ‘visuospatial difficulties’, when the brain has problems processing information about 3D objects. This can affect a person’s spatial awareness or the ability to judge distances. They may have difficulties using stairs, parking a car or recognising objects.

What causes misperceptions and misidentifications?

Even if the eyes of a person with dementia are healthy, their vision may be affected if the brain is damaged. Different parts of the brain process different types of information.

The occipital lobes at the back of the brain process visual information. If the occipital lobes become damaged, a person may find it hard to work out what they see in front of them. This causes misperceptions.

The brain’s temporal and parietal lobes are involved in recognising faces and objects, and in judging distances. So if those lobes become damaged, a person with dementia may have problems recognising faces or objects. This causes misidentification.

Who gets misperceptions and misidentifications?

Misperceptions and misidentifications increase with age because eyesight can get worse with age.

Older people are more likely to have poor eyesight, as well as long-term eye conditions such as glaucoma and macular degeneration. These can make their vision very blurry, or only allow them to see some of what they are looking at.

How does a person with dementia experience misperceptions and misidentifications?

Sometimes, the person may need to look twice at something to realise they were mistaken the first time. For example, they may think they have seen a spider in the corner of the room, but when they look again realise it is a shadow, or a mark on the wall.

If a person is experiencing misperceptions or misidentifications, they may mistake furniture or decorations for something more troubling. For example, they may understand a dark coloured doormat as a deep, black hole. This can make them feel nervous.

Some misperceptions and misidentifications can lead a person with dementia to make errors in how they use an object. For example, they may try to use a bus pass as a payment card, or not use the right coins to pay for something.

Supporting a person experiencing misperceptions and misidentifications

A person with dementia who is misperceiving or misidentifying things may feel unsure about their surroundings, and feel less confident and independent. You can support the person by reassuring them when they make mistakes, and build their confidence and willingness to go to new places.

If they do not notice that they are making mistakes, it could be that they lack insight into their dementia. They may become irritated or more easily frustrated if you point out mistakes. For more information see Understanding denial and lack of insight.

Familiar surroundings can be helpful to a person who is misperceiving or misidentifying. This is because they may rely more on memory and habit than on perception to move safely around their home. Try not to move furniture, or change where things are kept, as this can make it more difficult for them to relate to their space. 

If a person doesn’t understand what an object is, or appears not to recognise someone, try not to assume they have forgotten. They may be perceiving it as something different, or mistaking the person for someone else.

A person with dementia may disagree if you insist they have forgotten. To them, what they are seeing is correct. Most of the following tips will be helpful whether the person is experiencing misperception, misidentification, or memory problems:

Tips for supporting a person experiencing misperception or misidentification 

  • Speak to their GP if they often have misperceptions and misidentifications, especially if these are upsetting.
  • Try not to draw attention to their mistakes. Instead, gently remind the person of what is really in front of them. If they realise they have made a mistake, try to laugh about it together, if it feels appropriate. Being corrected can undermine their confidence, and they may become reluctant to join in conversations or activities.
  • If a person with dementia misidentifies someone, it can be distressing for everyone. If this happens, ask friends and relatives to introduce themselves when they arrive, and wear name stickers or tags. Try to reassure the person that everyone makes mistakes and find tactful ways to help them, including frequent name reminders or explanations about why people are there.
  • Try to keep doing the things they enjoy. For example, if they enjoyed reading but can’t due to problems with their vision, try audiobooks instead. For more information on activities and staying involved, see Keeping active and involved.
  • Try to be reassuring and help the person with dementia to feel safe. For example, they may be reluctant to cross a shiny floor, as it may appear to them as wet or icy. Offer them an arm, or lead them by walking ahead, so that they can see the floor is safe to walk on.
  • Improve lighting levels and reduce visual clutter to see if this helps. For example, an ornament’s shadow could resemble the ‘dog’ or ‘person’ they say they can see. This may be helped by simply changing the lighting.
  • If the person wears glasses or a hearing aid, make sure they are wearing them and that they are working correctly.
  • At mealtimes, it may help to tactfully describe the food and drink, where it is on the table and which cutlery to use. This may prevent them mistaking the jug of water for their glass, or something similar.
  • When passing something to a person with dementia, remind them how it is used.
  • Tell the person when someone enters or leaves the room, to avoid confusion and misidentification.

You can try to prevent or reduce misperceptions and misidentifications for a person with dementia at home. Making your home dementia friendly will help with practical tips.

For more information on how assistive technology can help, see Using technology to help with everyday life.

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