Development of the concepts of energy conservation and entropy

Development of the concepts of energy conservation and entropy was studied in children between 5 and 15 years of age. Energy conservation, as illustrated by the operation of double and colliding pendulums, was not well understood until about 15 years of age. Understanding of entropy was dependent on the particular apparatus used. When illustrated by the gradual mixing of rolling marbles of different colors, entropy was understood by 9- to 15-year-olds. But when illustrated by the eventual equalization of water levels in two interconnected containers, entropy was not well understood until about 15 years of age. Errors on a problem used to illustrate the conservation concept could often be characterized by the misapplication of the entropy concept and vice versa.     

Preservation of orthographic knowledge in aphasia

A simple untimed lexical decision task was designed to test implicit letter recognition in aphasic patients. Half of the nonwords used in this task were orthographically regular pronounceable pseudowords, and half were orthographically irregular unpronounceable letter strings. Twenty-five randomly chosen aphasic patients with mild to severe degrees of aphasia participated in the study. Although only six of the patients performed the lexical decision task successfully, all 25 demonstrated the ability to distinguish orthographically regular from irregular letter strings and, by implication, the ability to recognize and make use of the identities of written letters.     

Social loafing: Allocating effort or taking it easy?

When asked to work both alone and in groups, people exert less effort in groups, a phenomenon we call “social loafing.” Either of two possible strategies could explain this outcome: an allocational strategy where people work as hard as they can overall but conserve their strength for individual trials where work is personally beneficial and a minimizing strategy where the primary motive is to “get by” with the least effort possible. However, an allocational strategy would lead participants who always work in groups to put out as much effort as participants who always work alone, since there is no need to husband strength. Two studies using a sound production task found social loafing even under these conditions, suggesting that allocational strategies are not prevalent. Social loafing seems to occur when people perform together in groups, regardless of whether or not they must also perform alone.     

How big is big? Relative and absolute properties in memory

Previous studies of semantic memory have overlooked an important distinction among so-called “property statements”. Statements with relative adjectives (e.g., Flamingos are big) imply a comparison to a standard or reference point associated with an immediate superordinate category (a flamingo is big for a bird), while the truth of statements with absolute adjectives (e.g., Flamingos are pink) is generally independent of such a standard. To examine the psychological consequences of this distinction, we asked subjects in Experiment 1 to verify sentences containing either relative or absolute adjectives embedded in either predicate-adjective (PA) constructions (e.g., A flamingo is big (pink)) or predicate-noun (PN) constructions (e.g. A flamingo is a big (pink) bird), where the predicate noun was the immediate superordinate. Reaction times (RTs) and errors for relative sentences decreased when the superordinate was specified, but remained constant for absolute sentences. These data also suggest that the truth value of relative sentences depends, not just on the superordinate, but also on a more global standard for everyday, human-oriented objects. Experiment 2 extends these results in showing that ratings of the truth of relative sentences are a function of the difference in size between an instance and its superordinate standard (e.g., between the size of a flamingo and that of an average bird) and the difference between the instance and the standard for everyday objects. Experiment 3 replicated these findings using reaction time as the dependent measure.