Attentional bias modification for chocolate: Sham-n training as a new control group

Although attentional bias modification has been shown effective in several appetitive domains, results have been mixed. A major contributor seems to be the choice of control condition. The aim of the present study was to compare attentional bias modification for chocolate against a new control condition, sham-n (neutral or no-contingency) training. Using a modified dot probe protocol, participants (N = 192; 17–30 years) were randomly trained to attend to chocolate pictures, avoid chocolate pictures, or received sham-n training. In the attend and avoid conditions, stimulus pairs consisted of one chocolate and one non-chocolate picture, and probes replaced most often (90/10) chocolate or non-chocolate pictures, respectively. In the sham-n training condition, stimulus pairs consisted of two chocolate or two non-chocolate pictures, and probes replaced pictures within pairs with equal frequency (50/50). Attentional bias for chocolate increased following attend training, decreased following avoidance training, and did not change following sham-n training. The findings clearly demonstrate that both attend and avoidance training alter (in opposite direction) attentional bias for chocolate, whereas sham-n training is inert. This makes sham-n training particularly promising for use in clinical samples who tend to show strong initial biases.

Temporal expectancy in the context of a theory of visual attention

Temporal expectation is expectation with respect to the timing of an event such as the appearance of a certain stimulus. In this paper, temporal expectancy is investigated in the context of the theory of visual attention (TVA), and we begin by summarizing the foundations of this theoretical framework. Next, we present a parametric experiment exploring the effects of temporal expectation on perceptual processing speed in cued single-stimulus letter recognition with unspeeded motor responses. The length of the cue–stimulus foreperiod was exponentially distributed with one of six hazard rates varying between blocks. We hypothesized that this manipulation would result in a distinct temporal expectation in each hazard rate condition. Stimulus exposures were varied such that both the temporal threshold of conscious perception ( t 0 ms) and the perceptual processing speed ( v letters s −1 ) could be estimated using TVA. We found that the temporal threshold t 0 was unaffected by temporal expectation, but the perceptual processing speed v was a strikingly linear function of the logarithm of the hazard rate of the stimulus presentation. We argue that the effects on the v values were generated by changes in perceptual biases, suggesting that our perceptual biases are directly related to our temporal expectations.

Transposition in Young Monkeys and Children

30 young monkeys with discrimination learning experience and 30 first grade children were trained to discriminate stimulus pairs which differed in either brightness, volume, or volume plus brightness. After achieving the criteria of learning, Ss were tested for transposition on a fixed number of trials with stimulus pairs along the same dimension. The order of the near and far tests of transposition was counterbalanced. Both monkeys and children made the fewest errors in learning and transferring on the compound stimulus dimension. The most errors were made in learning and transfer on the brightness stimuli and on the far test condition. The analysis yielded no other significant sources of variance for children. However, the order of transposition testing, and the interactions of order × near-far test condition, stimulus dimension × near-far condition, and order × near-far × stimulus were significant sources of variance for the monkeys. Monkeys tested on the far test first made fewer errors on subsequent tests, and the magnitude of the reductions was most dramatic in the brightness condition. The results were interpreted in terms of stimulus differentiation in perceptual learning which assumes that relative differences among stimuli are valid sources of information.