%0 Journal Article
%T Increased Signal Complexity Improves the Breadth of Generalization in Auditory Perceptual Learning
%A David J. Brown
%A Michael J. Proulx
%J Neural Plasticity
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/879047
%X Perceptual learning can be specific to a trained stimulus or optimally generalized to novel stimuli with the breadth of generalization being imperative for how we structure perceptual training programs. Adapting an established auditory interval discrimination paradigm to utilise complex signals, we trained human adults on a standard interval for either 2, 4, or 10 days. We then tested the standard, alternate frequency, interval, and stereo input conditions to evaluate the rapidity of specific learning and breadth of generalization over the time course. In comparison with previous research using simple stimuli, the speed of perceptual learning and breadth of generalization were more rapid and greater in magnitude, including novel generalization to an alternate temporal interval within stimulus type. We also investigated the long term maintenance of learning and found that specific and generalized learning was maintained over 3 and 6 months. We discuss these findings regarding stimulus complexity in perceptual learning and how they can inform the development of effective training protocols. 1. Introduction Animals improve in the extraction and encoding of sensory information from the environment through perceptual learning. Psychophysical studies have established that practicing a task leads to specific improvements that are often restricted to stimuli used during training [1, 2].£¿ £¿While these paradigms typically utilise simple unisensory stimuli, the reverse hierarchy theory of perceptual learning is consistent with evidence that the ¡°default¡± setting in perception is one of higher order complex objects. For example, ecologically it is unusual to be presented with simple pure tones in isolation, but rather the complex frequency changes present in vocal communication such as birdsong and human speech [3¨C5]. Auditory research shows that while specific learning is found in most tasks, generalization to novel stimuli is generally restricted to spectral features of the stimuli [6¨C11]. In contrast, generalization to temporal stimulus features appears to be very limited, although it has been found for transferral from interval to duration within the same stimulus length, and onset/offset asynchrony, respectively [12, 13]. With regard to generalization to new intervals/durations, although Lapid and colleagues reported such generalization [14], this is in contrast with the majority of studies in which no such transfer of learning is found [11, 12, 15] with Lapid¡¯s study demonstrating generalization across stimulus types (Empty-Filled). This limitation of
%U http://www.hindawi.com/journals/np/2013/879047/