Duration of stability differences for words and pseudowords in the verbal transformation effect

Verbal transformation effect (VTE) refers to the phenomenon in which listening to the same word presented repeatedly leads to multiple interpretations (e.g. 'life life life...' becomes 'fly fly fly...'). Although there are several psychological models trying to account for VTE, the underlying neural mechanisms are largely unknown. Short-term synaptic depression (STD) is a related biophysical mechanism in that constant stimulation of a pre-synaptic neuron reduces the probability of a post-synaptic neuron firing due to neurotransmitter depletion. In addition, the rate of depression depends on whether the action potential activity between pre- and post-synaptic neurons is paired (paired activity results in a faster depression rate). We used 18 Turkish stem words and pseudowords as examples of paired and unpaired AP activity, respectively, in a standard VTE experiment paradigm and found that words remained stable approximately 400 ms shorter on average compared to pseudowords. This difference in stability durations may be due to faster depression of synapses in networks processing words, which suggests that STD could be considered as a suitable neural mechanism for VTE.