Evidence Reviewed as of before: 15-02-2023
Author(s)*: Tamara Lefranc; Audrey-Pascaline Segla
Editor(s): Annie Rochette
Table of contents


Agnosia is defined as the inability to recognize, identify and name familiar objects using one or more senses, or the inability to recognize one’s own deficits (anosognosia). This inability is not associated with a sensory impairment, but may be expressed specifically in one or more senses, such as sight (visual agnosia), hearing (auditory agnosia) or touch (tactile agnosia or astereognosia). Agnosia can also be characterized according to the nature of the object rather than the modality; for example, prosopagnosia is a form of visual agnosia where the person is unable to recognize faces. Agnosia affects less than 1% of the neurologically impaired population.

Patient/Family Information

What is agnosia?

Agnosia is defined as the inability to recognize, identify and name familiar objects using one or more of the senses, or the inability to recognize physical, cognitive and/or affective impairments (anosognosia). Agnosias are rare deficits, with less than 1% of people with neurological disorders suffering from agnosia.

Are there different types of agnosia?

Agnosia can be described as specific to the stimulus modality, such as sight (visual agnosia), hearing (auditory agnosia), smell (olfactory agnosia) or touch (tactile agnosia or astereognosia).

Visual agnosias are the most common and best-understood forms, divided into two main classes: aperceptive and associative visual agnosias.

Visual aperceptive agnosias are characterized by an inability to perceive the primary characteristics of objects. Sufferers are unable to copy shapes or objects. As for people with associative visual agnosia, they are unable to recognize the object despite perceiving all its features. So, even if they are able to copy or describe an object, they remain incapable of recognizing it, naming it, describing its function or using it.

Agnosia can also be characterized according to the nature of the object or stimulus rather than the modality, for example, prosopagnosia is a form of visual agnosia specific to the inability to recognize faces.

Another example of stimulus-specific agnosia is anosognosia, which is the inability to recognize the presence or severity of cognitive, sensory, motor or affective deficits.

The following table provides a non-exhaustive list of several forms of visual agnosia documented in the literature.

Table 1: Different forms of visual agnosia found in the literature
Stimulus-specific visual agnosia Description
Achromatopsia Inability to recognize colors.
Shape agnosia Inability to perceive the shape, orientation, length and contours of an object.
Integrative agnosia Inability to integrate features such as contours, shape, color and orientation as a whole to form an object.
Visuospatial agnosia Difficulty perceiving the spatial relationship between objects or between the object and oneself.
Akinetopsia Inability to perceive movement.
Agnostic alexia Language disorder consisting of the inability to recognize a word visually.
Topographical disorientation/ landmark agnosia Inability to orientate oneself in familiar surroundings due to inability to recognize landmarks once known.
Prosopagnosia Inability to recognize a familiar face or even one’s own face. In some cases, the person can deduce information such as age, gender and emotion, while others cannot recognize a face as one.
Simultagnosia Inability to perceive more than one object or object component at a time.
Balint syndrome Triad of symptoms including simultagnosia, ocular apraxia and ataxia.

Why do people become agnostic after a stroke?

The information captured by our senses is interpreted in different places in the brain according to its auditory, tactile, visual, olfactory or gustatory modality. In the event of a stroke, a brain lesion may occur in the regions linking the different primary sensory areas that interpret information from a specific modality, resulting in an inability to interpret the information that is perceived and, therefore, to recognize it. Depending on the location of the lesion, different forms of agnosia may occur.

For example, visual information captured by the eyes, such as colors, shapes, contours or movement, is interpreted in the brain by the primary visual cortex located in the occipital lobe. A lesion in the temporal, occipital or parietal lobes can result in visual agnosia. A lesion in the right temporal lobe could result in auditory agnosia.

What impact does agnosia have on my daily life?

All people carry out their activities of daily living by interacting with different elements in their environment. People with post-stroke visual agnosia may perceive the characteristics of familiar objects and environments differently from before the stroke. This can lead to feelings of confusion and insecurity when interacting with their environment on a daily basis, as they may perceive objects as obstacles rather than tools. Agnosia can also present a safety issue. For example, if a person with visual agnosia fails to recognize the sharp edge of a knife or road signs (making it impossible to drive safely), or if a person with olfactory agnosia fails to recognize the smell of a gas leak, smoke or burnt food.

Here are some other possible examples:

  • Difficulty recognizing familiar objects: can make simple daily activities difficult. For example, feeding oneself, choosing food at the grocery store, using tools at work, or getting dressed if the person doesn’t recognize his or her clothes.
  • Difficulties in social interaction: difficulty recognizing familiar faces (prosopagnosia) or understanding language due to difficulty recognizing words (auditory agnosia). This can lead to social isolation if not addressed by a professional.
  • Emotional impact: Living with agnosia can be stressful for the person, due to the constant challenges encountered. This can eventually lead to anxiety, depression and loss of self-confidence.

In short, agnosia can reduce a person’s autonomy, as they are unable to analyze their environment and interact with it adequately. Impacts vary according to the specific type of agnosia, and can have a significant impact on an individual’s quality of life.

Who diagnoses and treats agnosia?

The diagnosis of agnosia is made following medical imaging and neurological examination by a physician, most often a specialist in neurology. Agnosias can also be diagnosed following a neuropsychological examination, in which case the diagnosis is made by a neuropsychologist.

The resulting difficulties can be addressed in rehabilitation by the occupational therapist and speech language therapist.

Will my agnosia improve?

Few people recover their perceptual abilities. However, significant improvement may occur in the first 3 months post-stroke, and may continue to progress up to a year later. Recovery depends on a number of factors, including age, extent of disability, type, severity and location of stroke, and the effectiveness of therapies.

What therapies are available for agnosia?

Agnosia is a perceptual deficit for which the literature on interventions is scarce compared with other deficits such as hemineglect.

There are two types of approach, namely remedial and compensatory. The remedial approach consists in training the person’s cognitive abilities through exercises. The effectiveness of this approach has not been demonstrated in the literature.

There is currently no cure for agnosia. However, there are compensatory strategies that can help limit the impact on daily life. These strategies mainly involve using the other senses to compensate for modality-specific agnosia. Occupational therapists and speech therapists can help sufferers to adapt their environment and use compensatory strategies to assist recognition of environmental elements. In general, the use of compensatory strategies is accompanied by teaching about them, and training in the task to use them effectively.

Visual agnosias

These strategies include modifying the environment to facilitate recognition of objects relevant to the task, and to reduce risk. The strategies used must be adapted to the individual’s needs.

The organization of the environment is also a strategy that can help the person interact with his or her surroundings by purifying the space and organizing it in a way that assists recognition. Here are a few examples:

  • Lock rooms considered to be at risk, such as the garage;
  • Adding tactile cues to help the person recognize certain elements, such as a rough texture, can help identify dangerous objects by touch;
  • Organize the refrigerator so that fruits and vegetables can be found in an easily accessible place;
  • etc.

Auditory agnosia

In the case of auditory agnosias, compensatory strategies to improve the ability to communicate aim to compensate via the visual modality. This may involve using non-verbal cues such as intonation, facial expression or gestures to deduce the meaning of the conversation. They can also learn to lip-read. Reducing ambient noise can help the person to better understand their interlocutor. Adapting the environment can also help the person with auditory agnosia to identify risks in their environment, for example, by replacing an audible alarm with a flashing one.

Tactile agnosia

For tactile agnosias, it is generally recommended to compensate for object recognition using vision.


For anosognosia, self-awareness training is the most common type of intervention. Training can take the form of a formal intensive program, the modalities of which are indicated by the therapist, or recurrent follow-up with the therapist, in which the teaching and application of compensatory strategies are prioritized (e.g., presenting a stimulus in the attained direction and then in an unattained direction, splitting the task into small steps, etc.). The use of video self-observation can serve as a relevant tool for precipitating the patient’s awareness. In both cases, the aim is to improve the person’s ability to become aware of his or her difficulties in order to better compensate for them (e.g., using visual scanning methods to encourage the person to become aware of objects to his or her left in the case of hemineglect). In addition to training, some interventions combine personal training with education for the patient and those around him/her.

What can I expect from agnosia therapies?

Studies on the effectiveness of agnosia-specific interventions are few and far between. Thus, the level of scientific evidence is insufficient to date. What’s more, interventions are mainly aimed at compensating for agnosia on a day-to-day basis, rather than recovering perceptual skills.

How does agnosia affect my stroke recovery?

Anosognosia can limit a person’s ability to benefit from rehabilitation. Indeed, since they do not recognize the presence of their disabilities, they cannot devote their efforts to compensatory strategies, or see the relevance of therapy. However, there are strategies that can be used to help the person become aware of their difficulties.

A member of my family is agnostic. How can I help them?

Educate yourself: it’s beneficial for family members to learn about agnosia, its symptoms and its impact on daily life. Understanding the condition can help them better support their loved one.

Emotional support: Offering emotional support and encouragement is important. Listen to their frustrations and reassure your loved one. Being patient, understanding and empathetic is essential to overcoming the challenges associated with agnosia. In the case of anosognosia, it’s important to remain patient and avoid rushing your loved one and confronting them with their difficulties. This is even more likely to upset him/her.

Don’t forget to seek support for yourself, as a loved one.

Help, but not too much!

Depending on the severity of the agnosia, help may be needed with everyday tasks such as meal preparation, grocery shopping, personal care and leisure activities. Be careful not to do everything for your loved one.

It is possible to help the person with agnosia by adapting the environment to his or her needs to promote independence. This may involve organizing the refrigerator in a logical way, while helping the person to understand how his or her environment is organized. As a loved one, you have an important role to play in the person’s rehabilitation, and can help integrate the strategies learned in home therapy into everyday life. Therapists can guide you in the optimal strategies to use.

When working with a person with auditory agnosia, you can facilitate communication by adapting your approach. You could use gestures, writing, or make sure the environment is free of noises that interfere with communication.

Participate in rehabilitation: Interact with therapists and apply the strategies they teach to adapt the environment and/or activities in the community (e.g., reduce clutter, label objects, maintain good lighting to facilitate daily living). Keep them informed of your needs and the strategies that work with your loved one in their environment.


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