Children's Understanding of the Natural Numbers' Structure.

When young children attempt to locate numbers along a number line, they show logarithmic (or other compressive) placement. For example, the distance between "5" and "10" is larger than the distance between "75" and "80." This has often been explained by assuming that children have a logarithmically scaled mental representation of number (e.g., Berteletti, Lucangeli, Piazza, Dehaene, & Zorzi, ; Siegler & Opfer, ). However, several investigators have questioned this argument (e.g., Barth & Paladino, ; Cantlon, Cordes, Libertus, & Brannon, ; Cohen & Blanc-Goldhammer, ). We show here that children prefer linear number lines over logarithmic lines when they do not have to deal with the meanings of individual numerals (i.e., number symbols, such as "5" or "80"). In Experiments 1 and 2, when 5- and 6-year-olds choose between number lines in a forced-choice task, they prefer linear to logarithmic and exponential displays. However, this preference does not persist when Experiment 3 presents the same lines without reference to numbers, and children simply choose which line they like best. In Experiments 4 and 5, children position beads on a number line to indicate how the integers 1-100 are arranged. The bead placement of 4- and 5-year-olds is better fit by a linear than by a logarithmic model. We argue that previous results from the number-line task may depend on strategies specific to the task.

Language and Speech in Autism.

Autism is a developmental disability characterized by atypical social interaction, interests or body movements, and communication. Our review examines the empirical status of three communication phenomena believed to be unique to autism: pronoun reversal (using the pronoun you when the pronoun I is intended, and vice versa), echolalia (repeating what someone has said), and a reduced or even reversed production-comprehension lag (a reduction or reversal of the well-established finding that speakers produce less sophisticated language than they can comprehend). Each of these three phenomena has been claimed to be unique to autism; therefore, each has been proposed to be diagnostic of autism, and each has been interpreted in autism-centric ways (psychoanalytic interpretations of pronoun reversal, behaviorist interpretations of echolalia, and clinical lore about the production-comprehension lag). However, as our review demonstrates, none of these three phenomena is in fact unique to autism; none can or should serve as diagnostic of autism, and all call into question unwarranted assumptions about autistic persons and their language development and use.