The effect of type of behavior on behavior change caused by type of upcoming food substance

Previous research suggests that rats will decrease their consumption of a low-valued substance if a high-valued one will soon be available (anticipatory contrast), but will increase their rate of operant responding for a low-valued substance if a high-valued one will soon be available (positive induction). The present experiments tested whether rats would increase their operant rate of licking or lever pressing for 1% liquid-sucrose reinforcement when 32% sucrose reinforcement was upcoming in the same session. Results indicated that upcoming 32% sucrose increased rates of lever pressing for 1% sucrose, but did not produce similar increases in rates of licking. In fact, upcoming 32% sucrose significantly reduced lick rates in Experiment 2. The present results suggest that the different changes in behavior may be linked to the specific response that the subjects must engage in to obtain the reward (i.e., licking vs. lever pressing), and not to the function of the behavior (i.e., consummatory vs. operant) or to how frequently the substances are available (i.e., continuously vs. intermittently).     

Letter legibility and visual word recognition

Word recognition performance varies systematically as a function of where the eyes fixate in the word. Performance is maximal with the eye slightly left of the center of the word and decreases drastically to both sides of thisoptimal viewing position. While manipulations of lexical factors have only marginal effects on this phenomenon, previous studies have pointed to a relation between the viewing position effect (VPE) and letter legibility: When letter legibility drops, the VPE becomes more exaggerated. To further investigate this phenomenon, we improved letter legibility by magnifying letter size in a way that was proportional to the distance from fixation (e.g., TABLE). Contrary to what would be expected if the VPE were due to limits of acuity, improving the legibility of letters has only a restricted influence on performance. In particular, for long words, a strong VPE remains even when letter legibility is equalized across eccentricities. The failure to neutralize the VPE is interpreted in terms of perceptual learning: Since normally, because of acuity limitations, the only information available in parafoveal vision concerns low-resolution features of letters; even when magnification provides better information, readers are unable to make use of it.     

Object-based inhibition of return in static displays

After attention has been oriented to a location, inhibition mechanisms prevent the return of attention shortly afterward. This inhibition can be associated with an object in such a way that after cuing attention to the object, inhibition can move with the object to a new location. Recent research has noted that the object-based inhibition of return effect in moving displays is much smaller than the effect observed in static displays, and hence may be of little functional utility. However, we demonstrate that, on the contrary, the large effects observed in static displays are produced precisely because of the existence of object-based frames, which can be additive with location-based frames of reference.     

CAT: A tool for eliciting knowledge on how to perform procedures

Procedural tasks involve context-sensitive sequences of actions that are performed in pursuit of goals. Procedural knowledge specifies how to do something (e.g., repairing a car) but not how the physical system works (e.g., how the engine works). We have developed a computer program that elicits procedural knowledge from individuals with varying amounts of domain knowledge (ranging from novices to experts) and varying amounts of computer literacy. The tool is called CAT (cognitive analysis tool). CAT is an extension of a class of cognitive models known as GOMS, which stands for goals, operators, methods, and selection rules. The tool guides the user in articulating the goals (and subgoals) the user wants to accomplish, the operators (actions, steps) to accomplish each goal, the alternative methods of accomplishing goals, the conditions in which each method is applied, and exceptional circumstances when goals are suspended and restarted. CAT can be used on most IBMcompatible microcomputers.     

Mapping symbols to response modalities: Interference effects on Stroop-like tasks

Attention, Perception, & Psychophysics - Response compatibility effects were assessed with a Stroop-like task which involved arrow and word stimuli. The subjects were required to respond to one...