The cost of a strategy

Abstract

Experiment 1 demonstrated a new kind of dual-task interference effect. The primary task was a speeded left-right discrimination of stimulus position (R1). The un speeded secondary task consisted of reporting verbally whether the stimuli were the same or different (R2). Stimulus exposure time was either 150 or 2000 msec. Two groups of subjects performed the primary task only, whereas two other groups performed both tasks and were instructed to emit R1 before R2. It was reasoned that the decision would be made to emit R1 before R2, and that this decision would produce a lengthening of R1. The results supported this prediction. Experiment 2 showed that the interference effect also occurred when the subjects were not explicitly instructed to emit R1 before R2, and was not due to either the mere presence of the second task or to response grouping. Experiments 3 and 4 compared two possible models for explaining the interference effect, i.e. the capacity-sharing model and the postponement model. As predicted by the postponement model, task difficulty did not interact, or interacted underadditively, with task overlap (Experiment 3), and the interference effect was not influenced by the amount of processing resources devoted to the primary task (Experiment 4). It was concluded that this new type of interference effect is best explained by the version of the postponement model that locates the bottleneck at the decision stage.     

Preliminary analysis of effects of normal aging on different memory processes and abilities

Visual recognition-memory span, name-face association, and verbal memory with selective reminding were tested in two groups of 24 normal healthy volunteers (above and below age 50 yr.). The preliminary study suggests differential effects of aging on specific memory components and warrants careful exploration.     

Hand-hemispace spatial compatibility,precueing, and stimulus-onset asynchrony

Summary The role of attention and the resolution of coding conflicts in hand-hemispace spatial-compatibility effects was examined in a precueing experiment in which visual and vibrotactile precues, with various stimulus-onset asynchronies (SOAs), were presented in blocked and random order. It was expected that precues at the shorter SOAs would fail to facilitate the shifting of attention, as they occur too close to the imperative stimulus to be informative. The task would therefore approximate one of choice reaction time (RT), resulting in a hand-hemispace spatial-compatibility effect. Conversely, the longer SOAs would provide the subject with sufficient time in which to shift attention fully, and would therefore result in a task more like that of simple reaction time (SRT). It was expected that the hand-hemispace spatial-compatibility effect would then be absent. As was expected, this effect was present at the shorter SOAs, and absent at the longer SOAs. In Experiments 2 and 3, provision of a visual precue further facilitated attentional deployment, as did blocking the presentation of various SOAs in Experiment 3. Vibrotactile and visual precues did not differ in their ability to direct attention, implying that these modalities orient attention and precue location in essentially similar ways. These findings are discussed within the context of the mechanisms thought to underlie the time course of spatial compatibility and the dissipation of a fading trace of interfering spatial codes.     

Compatibility due to the coding of the relative position of the effectors

Response latencies emitted with the hands crossed are slower than those emitted with the hands uncrossed. Two explanations are available for the so-called crossed-hand effect. One attributes it to the non-natural posture of the arms in the crossed position, whereas the other is in terms of a conflict between the code describing the hand and the code describing its position. Experiment 1 disproved the postural hypothesis by showing that crossing the hands has no effect on response latencies in a simple reaction time task. Experiments 2 and 3 replicated the crossed-hand effect in a choice reaction time task and showed that it depends on the relative position of the two hands. In other words, responses are slower when the hand is located in the “wrong” position with respect to the other (e.g., the right hand is located to the left of the left hand), whereas the absolute position, that is the side of the body where the responding hand is located, does not seem to effect the speed of response.     

Correction to: Anaphoric Strategies Across Language Modalities: A Comparison Between Catalan and Catalan Sign Language (LSC)

Journal of Psycholinguistic Research - An amendment to this paper has been published and can be accessed via the original article.     

Bidirectional links in the network of multiplication facts

In three experiments, we tested the hypothesis that activation of multiplication operand nodes (e.g., 3 and 8) can occur through presentation of their product (e.g., 24). In Experiments 1 and 2 we found activation of the operands when the product was presented as a cue in a number-matching task. In Experiment 3, activation also occurred in a parity-matching task, where the product (24) was not relevant to the parity matching on its operands (3 and 8). We concluded that bidirectional links exist among the operands and their product for multiplication problems and these links can be activated in a purely stimulus-driven manner. We suggest this may constitute the basis for the solution of simple divisions by mediation through the complementary multiplication facts.     

Number magnitude orients attention, but not against one’s will

Recent evidence has shown that uninformative numbers can trigger attention shifts congruent with the spatial representation of number magnitude (Fischer, Castel, Dodd, & Pratt, 2003). In the present study, three spatial-cuing experiments whose aim was to qualify the automaticity of this numbermediated orienting are described. Experiment 1 replicated the phenomenon, showing that uninformative numbers can evoke orienting in a simple detection task. In Experiment 2, target location was random, but the participants were encouraged to shift attention to the left in response to large numbers and to the right in response to small numbers. No evidence for strong automaticity was observed, since the participants’ performance was better when left-side targets were preceded by large numbers than when they were preceded by small numbers and vice versa. Experiment 3 corroborated this pattern by comparing gaze- and number-mediated cuing under conditions of real counterpredictiveness. The results indicate that unlike gaze-driven orienting, number-mediated orienting is not obligatory.