A person seeing a design on the floor thought it was a fossil. It is an example of?

Appeared in: BHU NO - 2015

Explanation

An illusion is defined as a misinterpretation of a real sensory stimulus.
In the given scenario, there is a real stimulus present (the design on the floor).
The person misperceives this real stimulus, thinking it is something else (a fossil).
This perfectly matches the definition of an illusion.

Why Other Options Were Wrong

Option B: A delusion is a false, fixed belief, which is a disorder of thought content, not perception. The scenario describes a perceptual error, not a belief system.
Option C: A hallucination is a perception without an external stimulus. In this case, there is an external stimulus (the design on the floor).
Option D: An idea of reference is a specific type of delusion where one believes that random events are personally directed at them. The scenario does not involve this element.

Related Visual

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Disorders of Perception as background academic context rather than a clinical decision trigger.
Accurately differentiating between illusion, hallucination, and delusion is a fundamental skill in the Mental Status Examination (MSE) for any patient, especially in psychiatric or neurological settings.
Misidentifying these symptoms can lead to incorrect diagnosis (e.g., confusing a delirium-induced illusion with schizophrenia-related hallucination) and inappropriate treatment.
What if? If the patient saw the fossil on a blank wall where nothing existed, the phenomenon would be classified as a visual hallucination, suggesting a different underlying pathology (e.g., psychosis, substance withdrawal, or a neurological condition).

How to Approach the Question

First, analyze the stem to identify the core components of the experience described. The key elements are a real object ('a design on the floor') and a misinterpretation of that object ('thought it was a fossil').
Next, ask the key differentiating question: 'Is there a real, external stimulus present?' In this case, yes, the design exists.
Then, evaluate the options based on this finding. A perception without a stimulus is a hallucination. A false belief is a delusion. A misinterpretation of a real stimulus is an illusion.
Since the scenario involves misinterpreting a real stimulus, select the option that matches this definition.
Eliminate the other options. 'Delusion' and 'Idea of reference' are thought disorders, not perceptual ones. 'Hallucination' is incorrect because a stimulus is present.

Concept Tested & Keywords

Concept Tested: Disorders of Perception
Stem keywords: seeing a design, thought it was a fossil
Lead-in keywords: example of
Negative lead-in flag: false

Question ID

QrZL9t-pwRenpIkLytYp6

Reference Book

E6 Robert Boland, Marcia L. Verduin - Kaplan and Sadock's Comprehensive Text of Psychiatry-Wolters Kluwer Health (2024) (pp 1-16525 of 16525) pp. 3815-3817, 3250-3252

E6 Psychology Baron Misra 5e Part 1 p. 140-142

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