How can giving different names to visual forms affect the ability to discriminate them?

In the context of perceptual learning, the practice of assigning names to visual forms can significantly influence how easily they are discriminated. This phenomenon is often categorized into two distinct effects:1

• Acquired Distinctiveness: When vague or similar visual forms are given distinct, unique names, they become easier to discriminate. This may occur because the labels encourage the observer to analyze the sensory features of the stimuli more thoroughly, or because the observer begins to perceive a compound stimulus consisting of both the visual form and its associated label. If the labels differ, the resulting compound stimuli are perceived as different, thereby enhancing discrimination.1
• Acquired Equivalence: Conversely, if several distinct visual stimuli are assigned the same verbal label, their discriminability may be reduced.1

While these labelling effects are well-theorized, researchers have noted that experimental evidence for them can be fragile and the underlying factors are not yet fully understood. It remains a subject of study whether these improvements stem from a more active discovery of distinguishing characteristics or from the cognitive integration of labels with visual input.1