Unlike the degenerative disorders that cause dementias, which stem from a modest number of aberrant processes, aging-related cognitive changes reflect a host of mechanisms. These include mechanisms associated with a person’s condition, e.g., drugs, pain, depression, and sleep disorders. They include mechanistic changes linked to the aging process, e.g., enhanced neural network noise, increased neighborhood density, age of acquisition effects, degraded selective engagement of neural networks, alteration of the balance between volitional and reactive intention and attention, declines in neurotransmitter function, and brain ontogenesis over the life span. They include changes best characterized as senescent physiology and best demonstrated in decline in functions essential to episodic memory formation related to impaired encoding in the hippocampal cornu amonis (CA) fields and slowed neurogenesis in the hippocampal dentate gyrus. Finally, they include processes best characterized as senescent pathology, the best understood being degradation of myelin and associated reduction of central conduction velocities and slowing of processing speed. No longer should cognitive changes associated with aging be viewed as a simple manifestation of a unitary aging process. The large number of mechanisms at play and their complexity offer many opportunities for therapeutic intervention.

Is phonological form perceived, understood, stored, and accessed in the same way and with the same neural mapping in signed and spoken languages? This is the complex and multifaceted question that the work on sign language processing has addressed since the beginning. The methodologies and technologies used to address this question have become more sophisticated over the last sixty years. Since the beginning, a psycholinguistic tradition was at the center of the work on sign languages, and we trace the trajectory of this work in this chapter.

Every construction has a particular ecological location in the grammar network that is defined by its relationship to other constructions in the system. Since the relationships between constructions are similar to those between lexemes, Chapter 10 begins with a short discussion of psycholinguistic research on the mental lexicon, which is commonly analyzed as an activation network (Dell 1986). There is abundant evidence that lexical access is influenced by several interacting factors including frequency, priming, similarity and neighborhood density, or family size. Considering research on sentences processing, L1 acquisition and language change, the chapter argues that the availability, or accessibility, of constructions is influenced by the same factors as lexical access, that is, by frequency, priming, similarity and neighborhood density, supporting the hypothesis that lexemes and constructions are organized in similar ways. Specifically, the chapter argues that grammar includes “construction families” that influence the use and the development of syntactic patterns (Diessel and Tomasello 2005; Wells et al. 2009).

Every construction has a particular ecological location in the grammar network that is defined by its relationship to other constructions in the system. Since the relationships between constructions are similar to those between lexemes, Chapter 10 begins with a short discussion of psycholinguistic research on the mental lexicon, which is commonly analyzed as an activation network (Dell 1986). There is abundant evidence that lexical access is influenced by several interacting factors including frequency, priming, similarity and neighborhood density, or family size. Considering research on sentences processing, L1 acquisition and language change, the chapter argues that the availability, or accessibility, of constructions is influenced by the same factors as lexical access, that is, by frequency, priming, similarity and neighborhood density, supporting the hypothesis that lexemes and constructions are organized in similar ways. Specifically, the chapter argues that grammar includes “construction families” that influence the use and the development of syntactic patterns (Diessel and Tomasello 2005; Wells et al. 2009).