Ascending and descending stimulus runs are averaged to derive perceptual thresholds

Evidence

In an ascending series, the stimulus attribute value is first set well below the threshold and is then increased until the response changes. The attribute value where the response changes is called the ‘limit’. In a descending series, the opposite is performed: the stimulus attribute is decreased from a level well above the threshold until the response changes. The experiment consists of many runs in both directions, possibly distributed randomly. The average of all the obtained limits is taken as the threshold. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 917