Libet's intention reports are invalid: A replication of Dominik et al. (2017).

In the "Libet experiment" the onset of movement-related brain activity preceded the reported time of the conscious intention to move, suggesting that conscious intention may not play a role in initiating voluntary movements (Libet, Gleason, Wright, & Pearl, 1983). Dominik et al. (2017) provided evidence that the intention reports employed in the Libet experiment, which Libet et al. (1983) found to precede movement reports, are invalid. In the study by Dominik et al., intention reports preceded movement reports only when participants had prior experience making movement reports. Individuals without such experience reported intention around the same time as movement. These findings suggest that Libet's intention reports do not reflect experiences of intention, but, rather, inferences based on prior experience with movement reports. Our study replicated the core findings of Dominik et al. We argue that Libet's intention reports are invalid and explore the phenomenology of intention in the Libet experiment.

Sensation seeking predicts brain responses in the old-new task: converging multimodal neuroimaging evidence.

Novel images and message content enhance visual attention and memory for high sensation seekers, but the neural mechanisms associated with this effect are unclear. To investigate the individual differences in brain responses to new and old (studied) visual stimuli, we utilized event-related potentials (ERP) and functional Magnetic Resonance Imaging (fMRI) measures to examine brain reactivity among high and low sensation seekers during a classic old-new memory recognition task. Twenty low and 20 high sensation seekers completed separate, but parallel, ERP and fMRI sessions. For each session, participants initially studied drawings of common images, and then performed an old-new recognition task during scanning. High sensation seekers showed greater ERP responses to new objects at the frontal N2 ERP component, compared to low sensation seekers. The ERP Novelty-N2 responses were correlated with fMRI responses in the orbitofrontal gyrus. Sensation seeking status also modulated the FN400 ERP component indexing familiarity and conceptual learning, along with fMRI responses in the caudate nucleus, which correlated with FN400 activity. No group differences were found in the late ERP positive components indexing classic old-new amplitude effects. Our combined ERP and fMRI results suggest that sensation-seeking personality affects the early brain responses to visual processing, but not the later stage of memory recognition.

Brain potentials distinguish new and studied objects during working memory.

We investigated brain responses to matching versus nonmatching objects in working memory (WM) with a modified delayed match-to-sample task using event-related potentials (ERPs). In addition, ERP correlates of new items (new matches/new nonmatches) and previously studied items (studied matches/studied nonmatches) were examined in the WM task. Half of the common visual objects were initially studied until 95% accuracy was attained and half were new. Each memory trial began with the presentation of a sample object followed by nine test objects. Participants indicated whether each test item was the same as the object held in mind (i.e., match) or a nonmatch. Compared to studied matches, new matches evoked activity that was 50 ms earlier and largest at frontal sites. In contrast, P3 activity associated with studied nonmatches was larger than for new nonmatches at mostly posterior sites, which parallels previously reported old-new ERP effects. The ERP source analysis further confirms that the cortical mechanisms underlying matching objects and rejecting irrelevant objects during the task are both temporally and spatially distinct. Moreover, our current findings suggest that prior learning affects brain responses to matching visual items during a WM task.

Age effects on brain activity during repetition priming of targets and distracters.

The effects of age on repetition priming and how such differences were related to intentional learning and working memory status were examined. Fourteen older (age 65-75) and 14 younger (age 18-28) healthy adults performed a modified delayed match-to-sample task consisting of a target object held in mind followed by nine test objects. Sixty four-channel EEGs were recorded as participants indicated whether each test object was the same or different from the target object. Half of all target and distractor objects were intentionally studied prior to the task, and both target and distractor objects were repeatedly presented up to four times in each trial. Although both age groups showed repetition priming effects, speed increases due to repetition were more enhanced for elderly. ERP repetition effects for both younger and older adults were indexed via early (200-550) and late (550-850 ms) components. The early repetition effect was affected by whether a distractor was previously studied or not for younger but not for older adults. In contrast, the late repetition effect was not affected by prior intentional learning, and a marginal age effect suggested that repetitions of distractors likely affected older and younger adults differently. These findings suggest that at least two distinguishable repetition mechanisms differentially affect adult aging.

Bioelectrical potentials of Philodendron cordatum: a new method for investigation of behavior in plants.

We explored the prospect of using the bioelectrical potentiaLs of Philodendron cordatum as a new method for studying the behavior of plants. The bioelectrical potentials were recorded from equipment typically associated with EEG recordings. Plants were exposed to a 6-hr. training period of light only, dark only, or alternating 1-min. periods of light/dark. Following training, all plants were exposed to a 10-min. testing period in darkness during which bioelectrical potentials were recorded. Power of the bioelectric potentials was compared between groups of plants for frequencies between 0.1 and 10.0 Hz. Significant main effects of group and frequency were found, raising questions about the possibility of "learning" in P. cordatum.

Exploratory studies of classical conditioning of the preoral cavity in harnessed carpenter ants (Camponotus pennsylvanicus).

An attempt was made to classically condition the mouthparts of harnessed worker ants (Camponotus pennsylvanicus) in anticipation of feeding. Experiments were designed to investigate classical conditioning with one CS, discrimination between two CSs, and pseudoconditioning. Analysis indicated a small acquisition effect that could be accounted for by pseudoconditioning. The preparation can be used to study nonassociative learning and some instrumental conditioning situations.