Breaking a habit: A further role of the phonological loop in action control

Recent research has suggested that keeping track of a task goal in rapid task switching may depend on the phonological loop component of working memory. In this study, we investigated whether the phonological loop plays a similar role when a single switch extending over several trials is required after many trials on which one has performed a competing task. Participants were shown pairs of digits varying in numerical and physical size, and they were required to decide which digit was numerically or physically larger. An experimental cycle consisted of four blocks of 24 trials. In Experiment 1, participants in the task change groups performed the numerical-size judgment task during the first three blocks, and then changed to the physical-size judgment task in the fourth. Participants in the continuation groups performed only the physical-size judgment task throughout all four blocks. We found negative effects of articulatory suppression on the fourth block, but only in the task change groups. Experiment 2 was a replication, with the modification that both groups received identical instructions and practice. Experiment 3 was a further replication using numerical-size judgment as the target task. The results showed a pattern similar to that from Experiment 1, with negative effects of articulatory suppression found only in the task change group. The congruity of numerical and physical size had a reliable effect on performance in all three experiments, but unlike the task change, it did not reliably interact with articulatory suppression. The results suggest that in addition to its well-established role in rapid task switching, the phonological loop also contributes to active goal maintenance in longer-term action control.     

Humans (Homo sapiens) fail to show an inequity effect in an “up-linkage” analog of the monkey inequity test

Brosnan and de Waal (Nature 425:297–299, 2003) claimed that if a capuchin sees another capuchin receiving a superior food, she tends to reject an inferior, previously acceptable food. They related this phenomenon to human inequity aversion. This phyletic extension is “down linkage,” because nonhuman research is interpreted in terms of human research. The present experiment makes an “up-linkage” test of this claimed connection by attempting to reproduce the capuchin-inequity effect in humans. In Experiment 1’s equity condition, a subject and an adjacent confederate each clicked a computer mouse to mark the number “7” from a random numbers table, earning 0.5 yen per mark. In the inequity condition, the confederate’s pay rate was twice that of the subject. There was no between-condition difference in quitting times or likelihoods. Experiment 2 replicated Experiment 1 except, before beginning, the subject and confederate clicked a mouse over a rapidly switching message that said they would earn either 0.5 or 1 yen per marked seven. For the equity condition in this rigged test, subject and confederate stopped the message at 0.5 yen, while in the inequity condition, these values were 0.5 and 1 yen, respectively. Now, inequity-condition subjects quit sooner than equity-condition subjects. Experiment 1 found no inequity effect, but Experiment 2 did. These results show that: (a) a sense of control/responsibility may be critical to an inequity effect and (b) the inequity effect putatively present in capuchins cannot be reproduced in an up-linkage human analog of that research, thereby calling this linkage into question. This report exemplifies that up- and down-linkage tests are often requisite to establish commonality of psychological process between nonhuman primates and humans.     

Verbal representation in task order control: An examination with transition and task cues in random task switching

Recent task-switching studies in which a predictable task sequence has been used have indicated that verbal representation contributes to the control of task order information. The present study focused on the role of verbal representation in sequential task decisions, which are an important part of task order control, and examined the effects of articulatory suppression in a random-task-cuing paradigm with two different types of cues presented just before the presentation of a stimulus: a transition cue and a task cue. The former cue provided information only about switching or repeating the task, whereas the latter was associated directly with the identity of the task (i.e., indicating a parity or a magnitude task). In Experiment 1, in which transition cues guided task sequences, articulatory suppression impaired performance in both repetition and switch trials, thereby increasing the mixing costs. In Experiment 2, in which a task cue, rather than a transition cue, was presented to examine the influence of a cue-decoding process, articulatory suppression had no specific effect on task performance. Experiment 3, in which the transition cue and the task cue were randomly presented in the same block to equalize the memory load and task strategy for the two types of cues, confirmed that articulatory suppression significantly increased the mixing costs only in transition cue trials. The results from the three experiments indicated that the use of verbal representation is effective in sequential task decision—that is, in selecting a task set on the basis of transient task order information in both repetition and switch trials.     

Power imbalance,its legitimacy,and aggression

Sixty Japanese female students were asked to exchange shocks in electric roulette games with female opponents. The subjects were assigned to either the 80%, 50%, or 20% win conditions. Half of them were then led to judge that the power unbalance was legitimate by being informed that the assignment was based on a prior performance contest, with the good performer being assigned to the advantageous position. The other subjects were led to perceive the power imbalance as illegitimate by being informed that the assignment was randomly decided. The opponents always severely attacked them. The retaliation by the subjects was analyzed by a two-way ANOVA with Power Imbalance and Legitimacy. It was found that the subjects both in the 20% and 50% win conditions set more intense shocks to their opponents than those in the 80% win condition. This is not consistent with the fear of retaliation hypothesis which had predicted that the subjects would refrain from intensely aggressing against the opponent who had a greater aggressive capacity. It was also found that in the 80% win condition, the subjects set more intense shocks when the unbalance had been determined by their performance than when determined by luck, whereas in the 20% win condition, they set more intense shocks when the imbalance had been determined by luck than when determined by their performance. These suggest that retaliation depended upon perceived justifiability of aggression which was predicated on the legitimacy of the power imbalance. Finding in the 50% win condition that the shock settings were higher when the power imbalance had been determined by their performance than when determined by luck was interpreted in terms of their heightened competitiveness.     

The effect of number of kanji radical companions in character activation with a multi-radical-display task

The majority of Japanese complex kanji consist of two subword units (radicals), and each radical is differentiated according to its combinability. Radical-type frequency is defined as the number of radical companions (NC) functioning as the number of characters containing that radical. The current study is intended to address the question of whether the NC plays a role in kanji character activation under a multi-radical-display (MRD) instead of a tachistoscopic display. An MRD task was used in which the NC was manipulated and the frequency of use of the whole characters was matched on average across the experimental conditions. Participants were divided into two groups (good knowledge vs poor knowledge) according to the score of a kanji completion task. The participants' task was to select an appropriate combination of radicals to compose a legitimate character under the MRD condition. The poor-knowledge group yielded relatively more errors than did the good-knowledge group in the low-NC condition, whereas the good-knowledge group yielded more errors in the high-NC condition than in the low-NC condition. These results demonstrate the different influences of NC as metaknowledge (tacit knowledge of radical productivity) in both good and poor readers.     

I see into your mind too well: working memory adjusts the probability judgment of others' mental states

Although an increasing number of studies on adults have indicated that working memory (WM) contributes to the ability to understand the mental states of others (i.e., theory of mind), the detailed mechanism by which WM contributes to successful reasoning has not previously been revealed. This study shows that WM modulates the degree of attribution of one's own knowledge to others' mental states. Participants were asked to read a story twice (Experiment 2) or as carefully as possible (Experiment 3) and to estimate the probability percentages of possible choices for a naive protagonist's behavior. The participants were then asked to maintain either a two- or seven-letter alphabet string (i.e., a light or heavy WM load, respectively) during the probability estimation but not during the story comprehension. The results showed that compared to the participants with a light WM load, those with a heavy WM load estimated a significantly higher probability of the choice indicating that the protagonist would behave on the basis of a fact that the participants knew but the protagonist did not. This result indicates that WM moderates the extent to which adults attribute their own knowledge to others' mental states. The role of WM in theory of mind and in heuristic strategy for making probability judgments was then discussed.     

Time-shrinking: A discontinuity in the perception of auditory temporal patterns

Recent research at our laboratories in the field of human auditory time perception revealed that the duration of short empty time intervals (<～200 msec) is considerably underestimated if they are immediately preceded by shorter time intervals. Within a certain range, the amount of subjective time shrinking is a monotonous function of the preceding time interval: the shorter it is, the more it shrinks its successor. In the present study, the preceding interval was kept constant at 50 msec, and the following interval for which the duration had to be judged, varied from 40 to 280 msec. The results showed that at up to 100 msec, the perceived duration increased to a much lesser extent than did the objective duration. Beyond 120 msec, the perceived duration quickly increased and reached a veridical value at 160 msec. Such a sudden change of perceived duration in a temporal pattern in which the objective duration varies gradually indicates a typical example of categorical perception. We suggest that such a categorization of the time dimension might be a clue for processes of speech and music perception.