Not so primitive: context-sensitive meta-learning about unattended sound sequences

Abstract

Todd J, Provost A, Whitson LR, Cooper G, Heathcote A. Not so primitive: context-sensitive meta-learning about unattended sound sequences. J Neurophysiol 109: 99 -105, 2013. First published October 17, 2012 doi:10.1152/jn.00581.2012, an evoked response potential elicited when a "deviant" sound violates a regularity in the auditory environment, is integral to auditory scene processing and has been used to demonstrate "primitive intelligence" in auditory short-term memory. Using a new multiplecontext and -timescale protocol we show that MMN magnitude displays a context-sensitive modulation depending on changes in the probability of a deviant at multiple temporal scales. We demonstrate a primacy bias causing asymmetric evidence-based modulation of predictions about the environment, and we demonstrate that learning how to learn about deviant probability (meta-learning) induces context-sensitive variation in the accessibility of predictive long-term memory representations that underpin the MMN. The existence of the bias and meta-learning are consistent with automatic attributions of behavioral salience governing relevance-filtering processes operating outside of awareness. mismatch negativity; perceptual inference; salience; learning; auditory evoked potential HUMANS ARE ACCOMPLISHED at finding patterns in event sequences, an ability that is supported by automatic novelty detection mechanisms. In audition, automatic novelty detection is indexed by mismatch negativity (MMN), a fronto-central event-related potential (ERP) peaking 100 -200 ms after a novel event. The MMN, which is primarily generated in the auditory cortex, was first described by Näätänen, Gaillard, and Mäntysalo (1978) in an auditory oddball paradigm (e.g., a series of standard longer tones containing an occasional shorter oddball or deviant tone) through the use of deviant-standard difference waveforms. MMN is elicited automatically and is usually measured while participants attend to another modality (e.g., while reading or watching a silent movie), as it does not require attention but can be masked by attention-related ERPs. MMN amplitude is proportional to the difference between deviant and standard and is inversely proportional to the probability of the deviant. Early interpretations of the MMN (e.g., Näätänen and Michie 1979) were in terms of a mismatch between low-level auditory sensory memory traces of the standard and the deviant. However, mounting evidence has implicated much more sophisticated processing, leading Näätänen, Tervaniemi, Sussman, Paavilainen, and Winkler (2001) to characterize the MMN as a marker of "primitive intelligence" in the auditory cortex.Primitive intelligence is revealed by phenomena usually associated with higher-order cognition ranging from prediction and simple concept formation to mnemonic characteristics more associated with long-term memory than short-term sensory memory. For example, MMNs indicative of a left hemisphere specialization in extracting abstract rules are associated with violations of contingencies e...

What controls gain in gain control? Mismatch negativity (MMN), priors and system biases

“…The asymmetry or primacy bias was quantified by a Speed by Tone interaction in Todd et al (2013) that had a quite large effect size (Cohen's 1992, d = 1.4). Here we demonstrate that the primacy bias is anchored to what is happening at transition points in the sequence where one regularity switches to another.…”

“…As detailed in Todd et al (2013), sounds were 1,000-Hz pure tones presented binaurally over headphones at 75 dB SPL. Sounds were created with 5-ms rise/fall times and either a 20-ms or a 50-ms pedestal to produce 30-ms and 60-ms sounds, respectively.…”

“…Todd et al (2013) demonstrated an even longer-term influence by exploring how the bias was affected by alternating initial role assignment across sequence pairs. Participants heard three sets of slow followed by fast changing sequences with each pair separated by 5 minutes of silence.…”

“…we provide a test of these predictions of the differential sampling hypothesis by re-analysing data from the first sequence pair in Todd et al (2013) using ERP data separately extracted from the first and second half of each block within slow and fast sequences.…”

“…In this paper we detail how one theory-driven design -the multi-timescale paradigm -has produced results that expose a bias in the system. The bias demonstrates a powerful influence over MMN amplitude that is not a simple function of the probabilistic rarity or physical difference of the eliciting sound (Todd et al 2011;Todd et al 2013). By examining the change in MMN amplitude over time we test the way in which the multi-timescale sequence exposes the influence of prior experience on how the acoustic stream is filtered.…”