How do we know what we are doing? Time, intention and awareness of action

Time is a fundamental dimension of consciousness. Many studies of the "sense of agency" have investigated whether we attribute actions to ourselves based on a conscious experience of intention occurring prior to action, or based on a reconstruction after the action itself has occurred. Here, we ask the same question about a lower level aspect of action experience, namely awareness of the detailed spatial form of a simple movement. Subjects reached for a target, which unpredictably jumped to the side on some trials. Participants (1) expressed their expectancy of a target shift during the upcoming movement, (2) pointed at the target as quickly and accurately as possible before returning to the start posiment to the target shift if required and (3) reproduced the spatial path of the movement they had just made, as accurately as possible, to give an indication of their awareness of the pointing movement. We analysed the spatial disparity between the initial and the reproduced movements on those with a target shift. A negative disparity value, or undershoot, suggests that motor awareness merely reflects a sluggish record of coordinated motor performance, while a positive value, or overshoot, suggests that participants' intention to point to the shifting target contributes more to their awareness of action than their actual pointing movement. Undershoot and overshoot thus measure the reconstructive (motoric) and the preconstuctive (intentional) aspects of action awareness, respectively. We found that trials on which subjects strongly expected a target shift showed greater overshoot and less undershoot than trials with lower expectancy. Conscious expectancy therefore strongly influences the experience of the detailed motor parameters of our actions. Further, a delay inserted either between the expectancy judgement and the pointing movement, or between the pointing movement and the reproduction of the movement, had no effect on visuomotor adjustment but strongly influenced action awareness. Delays during either interval boosted undershoots, suggesting increased reliance on a time-limited sensory memory for action. The experience of action is thus strongly influenced by prior thoughts and expectations, but only over a short time period. Thus, awareness of our actions is a dynamic and relatively flexible mixture of what we intend to do, and what our motor system actually does.     

Undetected changes in visible stimuli influence subsequent decisions

Change blindness-our inability to detect changes in a stimulus-occurs even when the change takes place gradually, without any disruption [Simons, D. J., Franconeri, S. L., & Reimer, R. L. (2000). Change blindness in the absence of a visual disruption. Perception, 29(10), 1143-1154]. Such gradual changes are more difficult to detect than changes that involve a disruption. Using this method, David et al. [David, E., Laloyaux, C., Devue, C., & Cleeremans, A. (in press). Change blindness to gradual changes in facial expressions. Psychologica Belgica] recently showed substantial blindness to changes that involve facial expressions of emotion. In this experiment, we show that people who failed to detect any change in the displays were (1) nevertheless influenced by the changing information in subsequent recognition decisions about which facial expression they had seen, and (2) that their confidence in their decisions was lower after exposure to changing vs. static displays. The findings therefore support the notion that undetected changes that occur in highly salient stimuli may be causally efficacious and influence subsequent behavior. Implications concerning the nature of the representations associated with undetected changes are discussed.     

Emotional and learning behaviour in mice overexpressing heat shock protein 70

The effects of inducible heat shock protein 70 (HSP70) on emotional and learning behaviour as well as hippocampal long-term potentiation was investigated in transgenic HSP70 overexpressing mice. In active two-way avoidance learning (shuttle box) as well as spatial 8-arm radial maze learning, the HSP70 overexpressing mice showed diminished learning performance. In several tests there was no indication of differences in anxiety behaviour between transgenic mice and wild-type mice. This suggests that impairment in learning behaviour is unrelated to the learning task and motivational aspects of behaviour. To investigate the neurophysiological correlate of learning, long-term potentiation experiments were performed. In transversal hippocampal slices, an enhanced amplitude of the population spike was found in HSP70 overexpressing mice. It was hypothesised that enhanced potentiation in conjunction with potentiation effects due to learning led to learning impairment.     

Further evidence for systematic reliability differences between explicit and implicit memory tests

Meier and Perrig (2000) as well as Buchner and Wippich (2000) have shown that simple dissociations between explicit and implicit memory measures need not reflect functional dissociations of hypothetical underlying memory systems. Instead, such dissociations may also result from the fact that some widely used implicit memory measures are simply less reliable than the explicit measures with which they have been compared. We extend this argument in two ways. First, we show that illusion-based memory measures such as the priming measures derived from fame andpreference judgement tasks are also subject to the reliability problem. Second, we show that yes-no and two-alternative forced-choice paradigms should, and in fact do, yield virtually identical results as far as the reliability of the memory tests is concerned.     

Implementing communication between Windows PCs and test equipment using RS-232 and Borland C++ Builder.

Modern experiments in the behavioral sciences frequently employ several items of electronic equipment such as computers, monitoring devices, stimulus presentation equipment, and response collection systems. In many cases it would be advantageous for these items to communicate directly with each other. Such communication may facilitate greater automation of experiments (i.e., reduced experimenter influences during the experiment), more precise experiment control (i.e., superior timing and synchronization capabilities of electronic devices), and greater accuracy of data collection (i.e., reduced ambiguity of participant responses). Many electronic experiment devices already provide external interfaces through which communication with other devices can be implemented. The most common is based on the RS-232 protocol, which is also found in all standard PCs. Therefore, Microsoft Windows based computers can be programmed to control experiments by communicating directly with electronic experiment devices. We show how to implement this RS-232 interconnection between devices and a Windows PC using currently available software tools.     

Me or not me – An optimal integration of agency cues?

Recent work has demonstrated that the sense of agency is not only determined by efference-copy-based internal predictions and internal comparator mechanisms, but by a large variety of different internal and external cues. The study by Moore and colleagues [Moore, J. W., Wegner, D. M., & Haggard, P. (2009). Modulating the sense of agency with external cues. Conscious and Cognition] aimed to provide further evidence for this view by demonstrating that external agency cues might outweigh or even substitute efferent signals to install a basic registration of self-agency. Although the study contains some critical points that, so we argue, are central to a proper interpretation of the data, it hints at a new perspective on agency: optimal cue integration seems to be the key to a robust sense of agency. We here argue that this framework could allow integrating the findings of Moore and colleagues and other recent agency studies into a comprehensive picture of the sense of agency and its pathological disruptions.     

Age‐related changes in the control of episodic retrieval: an ERP study of recognition memory in children and adults

We examined developmental aspects of the ability to monitor the temporal context of an item’s previous occurrence while event‐related potentials (ERPs) were recorded. In a continuous recognition task, children between 10 and 12 years and young adults watched a stream of pictures repeated with a lag of 10–15 intervening items and indicated recurrences. In a second run, these already familiar pictures were repeated as non‐targets along with new pictures, while subjects were instructed to indicate only recurrences within the run. Young adults were able to maintain high performance levels in both tasks, whereas children had longer response times and committed a large number of false alarms to non‐targets. ERPs in both age groups showed similar parietal old/new effects for target repetitions within runs. In addition, adults’ ERPs showed similar old/new effects at frontal electrodes for repetitions and non‐targets, presumably reflecting assessments of familiarity, whereas for children repeated relative to first presentations were associated with more negative‐going waveforms at anterior frontal recording sites. Together, these results suggest a continuing maturation of the brain networks assessing novelty or familiarity. Recollection as indexed by parietal old/new effects appeared similar between young adults and children, but the development of controlled episodic retrieval, resulting in recollection of non‐target information, appears to continue well into adolescence.     

Visual pattern matching: Effects of size ratio, complexity, and similarity in simultaneous and successive matching

An experiment on mental transformation of size, in pairwise comparison of simultaneously or successively presented figures with respect to shape, is reported. Regardless of type of presentation (simultaneous vs. successive), figural complexity, and similarity within pairs of different-shaped figures, median latencies of both same and different responses were approximately linearly increasing functions of the linear size ratio between the patterns to be compared. The slopes of the functions showed significant effects of figural complexity and similarity for simultaneous but not for successive matching. The results suggest that successive matching was done by encoding a subpattern of the first stimulus in a pair as a mental image, transforming the image to the size format of the other stimulus, and then testing for a match; in simultaneous matching the process of encoding, transformation, and comparison appeared to be executed several times for each pair of figures. The interpretation was illustrated by a random walk model, which provided a good fit to the results. Received: 31 March 1998 / Accepted: 22 August 1998     

Implicit change identification: a replication of Fernandez-Duque and Thornton (2003)

Using a simple change detection task involving vertical and horizontal stimuli, I. M. Thornton and D. Fernandez-Duque (2000) showed that the implicit detection of a change in the orientation of an item influences performance in a subsequent orientation judgment task. However, S. R. Mitroff, D. J. Simons, and S. L. Franconeri (2002) were not able to replicate this finding after correcting for confounds and thus attributed Thornton and Fernandez-Duque's results to methodological artifacts. Because Mitroff et al.'s failure to replicate might in turn have stemmed from several methodological differences between their study and those of Thornton and Fernandez-Duque (2000) and Fernandez-Duque and Thornton, the current authors set out to conduct a further replication in which they corrected all known methodological biases identified so far. The results suggest that implicit change detection indeed occurs: People's conscious decisions about the orientation of an item appear to be influenced by previous undetected changes in the orientation of other items in the display. Implications of this finding in light of current theories of visual awareness are discussed.