A Linguist Explains: Why We Forget Words We Know

"How do you say this in English?" - I ask often, knowing the word, but forgetting it in the moment. "Wait, I know this word. I can't think of it now. BRAINFOG." - I say frantically trying to remember the word, more often than not.

There are few experiences as universally frustrating as forgetting a word you know perfectly well. You are in the middle of a conversation, perhaps telling a story or explaining an idea, when the word you need suddenly disappears. You know that you know it. You may even remember its first letter, how many syllables it has, or another word that sounds similar. Yet the word itself remains just beyond reach, only to resurface minutes later when the conversation has already moved on. It can be very frustrating.

Most of us dismiss these moments as absent-mindedness or signs of distraction. As we get older, we may even worry that they signal declining memory. From a linguistic perspective, however, these temporary lapses tell a very different story. Rather than revealing a failure of language, they offer a fascinating window into the remarkable complexity of the human mind and the intricate way in which words are organized, stored, and retrieved.

One of the most influential ideas in psycholinguistics is that our vocabulary is not stored in the brain like entries in a dictionary. Instead, linguists speak of a mental lexicon, an immense network in which every word is connected to countless others through sound, meaning, grammatical properties, emotional associations, and personal experience. The English word tree, for instance, is connected not only to forest, leaf, and wood, but also to childhood memories, books we have read, places we have visited, different trees we have seen, and perhaps even songs or films. Every new experience subtly reshapes these connections, making our mental lexicon one of the most dynamic systems in human cognition.

This network allows us to produce language at astonishing speed. During ordinary conversation, our brains retrieve two or three words every second without conscious effort. Behind what feels like effortless speech lies an extraordinary sequence of cognitive operations. We begin with an idea, select the appropriate concept, activate the corresponding word, retrieve its grammatical information, assemble its sounds, and coordinate the muscles required for articulation, all within a fraction of a second. Most of the time, this process is so efficient that we remain blissfully unaware of it. It is only when something momentarily interrupts the chain that we catch a glimpse of the machinery beneath fluent speech.

Psychologists refer to these interruptions as the tip-of-the-tongue phenomenon (TOT). First described systematically in the 1960s and studied extensively ever since, tip-of-the-tongue states occur when speakers successfully access the meaning of a word but temporarily fail to retrieve its phonological form. Importantly, the word has not disappeared from memory. Research consistently shows that people experiencing a TOT state often know a surprising amount about the missing word. They may correctly identify its initial sound, estimate its number of syllables, or recognize it immediately when someone else says it. These findings suggest that different aspects of lexical knowledge are stored and accessed separately. Knowing a word's meaning and retrieving its pronunciation are closely related processes, but they are not identical.

The British linguist Jean Aitchison, whose work on the mental lexicon remains essential reading for everyone interested, compares our vocabulary to a densely interconnected web rather than a simple list. In such a system, retrieving one word often activates many related alternatives. Sometimes these alternatives compete with one another, slowing the retrieval process just enough to produce the familiar sensation that a word is "on the tip of the tongue." What feels like forgetting is often the consequence of an overactive system rather than an underperforming one.

This complexity becomes even more apparent in multilingual speakers. People who use two or more languages frequently report experiencing word-finding difficulties more often than monolingual speakers, leading some to wonder whether bilingualism somehow weakens memory. The evidence suggests precisely the opposite. Bilingual speakers keep multiple linguistic systems active simultaneously, even when using only one language. Every time a bilingual person speaks English, for example, words from Spanish, Italian, Mandarin, or Arabic remain partially activated in the background. The brain must therefore accomplish two tasks at once: selecting the correct word while inhibiting competing alternatives from another language.

Far from indicating confusion, this constant management reflects an impressive degree of cognitive flexibility. Studies by Tamar Gollan and colleagues suggest that the occasional increase in tip-of-the-tongue experiences among bilinguals is a natural consequence of navigating multiple lexical systems, not a sign of poorer language ability. In other words, bilingual speakers are not forgetting more words because they know less, but they are managing a larger and more interconnected linguistic repertoire.

Age also plays an important role in how we retrieve words, although perhaps not in the way many people imagine. Healthy older adults generally possess larger vocabularies than younger adults, having accumulated decades of reading (one hopes!), conversation, and experience. Yet they also report more frequent word-finding difficulties. Rather than reflecting a shrinking vocabulary, these delays appear to result from slower access to an increasingly extensive mental lexicon. A useful analogy is that of a library. A library with ten thousand books is easier to search than one containing a million volumes. The collection has grown richer, but locating a particular title may occasionally require a little more time.

Our everyday circumstances also influence lexical retrieval. Fatigue, stress, anxiety, and divided attention all increase the likelihood of experiencing TOT states. This explains why an elusive word often appears only after we have stopped actively searching for it. During a walk, while making dinner, or just before falling asleep, the missing word suddenly emerges without effort. Although this phenomenon may seem mysterious, cognitive psychologists argue that shifting our attention reduces interference from competing words, allowing the correct lexical pathway to become active once again.

Ultimately, moments of forgetting reveal something remarkable about language. They remind us that speaking is not the simple retrieval of isolated words but the coordinated activity of one of the most sophisticated cognitive systems humans possess. Every conversation requires the brain to integrate memory, attention, grammar, pronunciation, meaning, and social context almost instantaneously. That this process occasionally hesitates is perhaps less surprising than the fact that it works so flawlessly most of the time.

The next time a familiar word escapes you, it may be worth resisting the temptation to see it as a failure. Instead, consider it a beautiful flaw of a greater system. For a few seconds, the effortless illusion of fluent speech disappears, revealing the astonishing complexity of the mental lexicon that makes language possible.

Further Readings:

1. Aitchison, J. (2012). Words in the Mind: An Introduction to the Mental Lexicon (4th ed.). Wiley-Blackwell.
2. Brown, A. S. (1991). "A Review of the Tip-of-the-Tongue Experience." Psychological Bulletin, 109(2), 204-223.
3. Gollan, T. H., & Brown, A. S. (2006). "From Tip-of-the-Tongue (TOT) Data to Theoretical Implications in Two Languages." Bilingualism: Language and Cognition.

To Watch: just copy these in your browser

1. TED-Ed: "How Memories Form and How We Lose Them."
2. Crash Course Psychology: "Memory."
3. The Ling Space: "The Mental Lexicon."