Selective Attention: The Cocktail Party Effect, Theories and Tests

By the IQ Revealed Team · Updated October 17, 2026

Selective attention is the ability to focus on the information that matters for what you are doing and filter out everything else. It is how you follow one voice in a noisy room, read on a busy train or spot a friend in a crowd. Your senses take in far more than the brain can handle consciously, so attention selects. The price of that filter is that some of what it rejects never reaches awareness at all.

The cocktail party effect

The classic example is a party: many people talking, yet you can follow the one you are listening to. In 1953 the British engineer Colin Cherry studied this with headphones. He played a different message to each ear and asked listeners to repeat one of them aloud as they heard it, a method called shadowing. Listeners could do it, but they could say very little about the other message afterwards.

Your own name gets through. In 1959 Neville Moray found that listeners could report almost nothing from the ignored ear, even a short list of words repeated many times, and that specific instructions to listen for numbers did not help. The one thing that broke through was the listener’s own name.
But only for about a third of people. Moray’s study and a larger 1995 replication both found that roughly 33% of listeners report hearing their own name in the message they are ignoring.

That second finding matters: the filter is not the same for everyone, and the differences turn out to be linked to working memory (see below).

How the filter works: four theories

Psychology’s long argument about selective attention is about when the selection happens.

Early selection (Broadbent, 1958). Donald Broadbent proposed a filter that picks one channel on physical features (which ear, which voice, which pitch) and blocks the rest before their meaning is processed. It explains shadowing well, but not why your name gets through.
Attenuation (Treisman, 1960s). Anne Treisman found that when two shadowed passages switched ears mid-sentence, listeners sometimes repeated a word or two from the wrong ear, following the meaning. She concluded that the filter turns rejected messages down rather than off, so words that are important or expected can still reach awareness.
Late selection (Deutsch & Deutsch, 1963). All input is processed for meaning, and selection happens only at the point of response or memory.
Load theory (Lavie, 1995). Nilli Lavie argued that both camps were partly right. When the main task is easy, spare capacity spills over and distractors get processed; when it is demanding, there is no spare capacity left and distractors are filtered out early. Later researchers have questioned how cleanly load can be separated from other factors, but the core idea is widely used.

Selective attention in vision

Vision works the same way. Attention is often described as a spotlight that boosts whatever it falls on. In Treisman and Garry Gelade’s feature-integration theory (1980), a target that differs by one simple feature, such as a red dot among green ones, “pops out” at once, while a target defined by a combination of features, such as a red X among red Os and green Xs, needs attention to move from item to item, so search takes longer the more items there are.

The flip side is inattentional blindness: when attention is locked onto one task, even a person in a gorilla suit walking through the scene can go unseen. That page covers the famous experiment and its real figures, so it is not repeated here.

Selective vs sustained vs divided attention

Selective attention: choosing what to process and ignoring the rest.
Sustained attention: keeping focus over time, covered on our page about attention span.
Divided attention: doing two things at once. Because capacity is limited, splitting it usually costs speed or accuracy on both tasks; our page on cognitive load explains why.

How selective attention is tested

The Stroop test (1935). Name the ink colour of colour words. When the word and the ink disagree (RED printed in blue), people are slower, because reading is automatic and has to be suppressed.
The flanker task (1974). Respond to the central letter or arrow while ignoring those beside it. Conflicting flankers slow responses.
Dichotic listening. Cherry’s two-ear method, still used to study auditory attention.
Visual search. Find a target among distractors; the time it takes shows how attention moves across a scene.
Cancellation tests. The d2 test, created by Rolf Brickenkamp in Germany in 1962 to help select drivers and revised in 2010, asks you to cross out every letter d with exactly two marks in rows of similar-looking d’s and p’s, with 20 seconds per row. Versions are used in traffic, clinical and occupational assessment.

Is selective attention related to IQ?

Partly, and mostly through working memory. In the 2001 replication of the cocktail party study by Andrew Conway, Nelson Cowan and Michael Bunting, the people who heard their own name in the ignored message tended to have lower working memory capacity, which the authors read as difficulty blocking out distraction. Working memory and the control of attention are, in turn, closely related to reasoning ability, and both sit within executive function.

There is an important limit. The tasks that show attention effects most reliably across groups are often poor at ranking individuals: a 2018 study of seven classic tasks, including Stroop and flanker, found test-retest reliabilities ranging from 0 to .82, surprisingly low for most. A test that does not rank people consistently cannot correlate strongly with IQ or anything else. So a single Stroop score says little about how intelligent someone is, and an IQ score says little about how well they can concentrate in a noisy office.

Can you improve it?

Reduce the competition. The most reliable gain comes from removing distractors: phone out of sight, notifications off, one tab open.
Make the task engaging. Load theory predicts that a task that fully occupies you leaves less spare capacity for distraction.
Be sceptical of brain-training claims. Practice on an attention game improves that game; evidence that it carries over to everyday focus or to IQ is weak, as our page on whether video games make you smarter explains.

Trust and scope notes

This page summarises published research for general information, with figures taken from the studies listed below. Nothing here is medical advice, and no single attention test diagnoses a condition. The IQ Revealed test is an online reasoning test of 40 original items for adults aged 18 and over; it is not a clinical assessment and it does not measure attention. Our guide to how IQ tests work explains what an online test can and cannot tell you.

IQ Revealed is not affiliated with, endorsed by or connected to the researchers, universities, journals or publishers named on this page, or to Hogrefe or the authors of the d2 test. Names are used only to identify the research and instruments being described.

Frequently asked questions

What is selective attention?＋

Selective attention is the ability to focus on what matters for the task in hand while filtering out everything else competing for your senses. Following one conversation in a noisy room, reading while a television is on, or looking for a friend in a crowd all depend on it. The brain cannot process everything at once, so it selects.

What is the cocktail party effect?＋

The cocktail party effect is the ability to follow one voice among many, and the way certain sounds, above all your own name, can still grab your attention from a conversation you were ignoring. The British engineer Colin Cherry studied the first part in 1953; in 1959 Neville Moray found that a listener's own name was the one thing that broke through from an ignored message. Later studies put that at about a third of listeners.

What are the main theories of selective attention?＋

Donald Broadbent's filter model (1958) said attention blocks unattended information early, on physical features such as which ear or which voice. Anne Treisman's attenuation model (1960s) said ignored information is turned down rather than blocked, so important words can still get through. Deutsch and Deutsch (1963) proposed late selection, after meaning has been processed. Nilli Lavie's load theory (1995) reconciled them: whether distractors get processed depends on how demanding the main task is.

What is the difference between selective, sustained and divided attention?＋

Selective attention is choosing what to focus on and ignoring the rest. Sustained attention is keeping that focus over time. Divided attention is splitting focus between two tasks at once, which usually costs accuracy on both. They are related, but tests can measure them separately.

How is selective attention tested?＋

Common laboratory tasks include the Stroop test (naming the ink colour of a colour word, such as the word RED printed in blue), the Eriksen flanker task (responding to a central arrow while ignoring the arrows beside it), dichotic listening (two messages, one to each ear), and visual search. Clinical and selection settings also use paper cancellation tests such as the d2 test, first published in Germany in 1962.

Are people with higher IQ better at selective attention?＋

There is a link, mostly through working memory. In a 2001 study, people who noticed their own name in a message they were supposed to ignore tended to have lower working memory capacity, suggesting they found it harder to block distraction. But many classic attention tasks measure individual differences poorly: one 2018 study found test-retest reliabilities ranging from 0 to .82 for seven of them, which limits how strongly any of them can correlate with IQ.