Cold pressor stress reduces left cradling preference in nulliparous human females

The left cradling preference refers to the finding that women hold their infants more frequently on the left side of their own bodies. Several observational studies showed reduced left cradling during stressful circumstances, such as mother-infant separation, or domestic violence. However, until now no experimental study was conducted to investigate the immediate impact of stress on cradling behaviour. Half of the 64 female subjects participating were randomly assigned to a stressful bilateral cold pressor test. The remaining subjects performed a non-stressful control procedure. Before and after this intervention, cradling behaviour was assessed using a baby-like doll. Subjects showed a left cradling preference prior to the intervention. The cold pressor test increased blood pressure and heart rate significantly. A repeated ANOVA revealed an interaction of intervention (cold pressor vs. control) X assessment period (pre- vs. post-intervention), indicating that cold pressor stress reduces left cradling behaviour in female volunteers. Our data indicate that stress influences cradling preference. This may be of relevance for caregiver-infant interactions.     

Do Lemmas Speak German? A Verb Position Effect in German Structural Priming

Lexicalized theories of syntax often assume that verb‐structure regularities are mediated by lemmas, which abstract over variation in verb tense and aspect. German syntax seems to challenge this assumption, because verb position depends on tense and aspect. To examine how German speakers link these elements, a structural priming study was performed which varied syntactic structure, verb position (encoded by tense and aspect), and verb overlap. Abstract structural priming was found, both within and across verb position, but priming was larger when the verb position was the same between prime and target. Priming was boosted by verb overlap, but there was no interaction with verb position. The results can be explained by a lemma model where tense and aspect are linked to structural choices in German. Since the architecture of this lemma model is not consistent with results from English, a connectionist model was developed which could explain the cross‐linguistic variation in the production system. Together, these findings support the view that language learning plays an important role in determining the nature of structural priming in different languages.     

Effector system-specific sequential modulations of congruency effects

Congruency effects in conflict tasks are reliably reduced after experiencing conflict, that is, following incongruent trials. Such sequential modulations (sometimes referred to as the Gratton effect) indicate the operation of conflict adaptation mechanisms. The influential conflict monitoring hypothesis suggested that after conflict the processing of relevant stimulus dimensions is increased. Alternatively, it was suggested that the influence of automatic response activation is suppressed following conflict. In two experiments, participants worked on the same cognitive task (Experiment 1: Eriksen flanker; Experiment 2: Simon) with the same kind of stimulation. A cue indicated whether they should respond with the hands or the feet. When the effector system repeated from the previous trial, a sequential modulation was reliably observed. When the effector system switched, however, the sequential modulation collapsed. These results are taken to argue for the suppression of effector system-specific response activations as a consequence of experiencing conflict. Alternative interpretations in terms of task-set and/or context switches are discussed.     

Another look at retroactive and proactive interference: A quantitative analysis of conversion processes

Traditionally, the causes of interference phenomena were sought in “real” or “hard” memory processes such as unlearning, response competition, or inhibition, which serve to reduce the accessibility of target items. I propose an alternative approach which does not deny the influence of such processes but highlights a second, equally important, source of interference—the conversion (Tulving, 1983) of accessible memory information into memory performance. Conversion is conceived as a problem-solving-like activity in which the rememberer tries to find solutions to a memory task. Conversion-based interference effects are traced to different conversion processes in the experimental and control conditions of interference designs. I present a simple theoretical model that quantitatively predicts the resulting amount of interference. In two paired-associate learning experiments using two different types of memory tests, these predictions were corroborated. Relations of the present approach to traditional accounts of interference phenomena and implications for eyewitness testimony are discussed.     

The Simon effect in cognitive electrophysiology: A short review

In the Simon task, stimuli are presented laterally and typically a non-spatial stimulus dimension demands a lateralized choice response. Responses are faster when the task-irrelevant stimulus location and the response location correspond than when they do not correspond. The present paper explores the impact of the Simon task on cognitive electrophysiological research as well as the insights gained from event-related brain potentials (ERPs) in the attempt to uncover the hidden mechanisms underlying the Simon effect.     

On the temporal organization of facial identity and expression analysis: Inferences from event-related brain potentials

In the present study, behavioral and electrophysiological markers of information processing—the lateralized readiness potential, the N170, and the P300—were recorded in order to assess the functional and temporal organization of facial identity and expression processing. A two-choice go/no-go task was used in which facial expression (happy vs. angry) determined response hand and response execution depended on facial familiarity (familiar vs. unfamiliar). The duration of facial identity and expression processing was manipulated in separate experiments. Together, the present findings in measures of overt and covert response activation indicate that facial identity is analyzed in parallel with, and typically somewhat faster than, facial expression. These data support a parallel model of face perception that assumes partial output from facial identity and expression processes to motor activation processes.     

Motor limitation in dual-task processing under ballistic movement conditions

The standard bottleneck model of the psychological refractory period (PRP) assumes that the selection of the second response is postponed until the first response has been selected. Accordingly, dual-task interference is attributed to a single central-processing bottleneck involving decision and response selection, but not the execution of the response itself. In order to critically examine the assumption that response execution is not part of this bottleneck, we systematically manipulated the temporal demand for executing the first response in a classical PRP paradigm. Contrary to the assumption of the standard bottleneck model, this manipulation affected the reaction time for Task 2. Specifically, reaction time for Task 2 increased with execution time for Task 1. This carryover effect from Task 1 to Task 2 provides evidence for the notion that response execution can be part of the processing bottleneck.     

Control over speeded actions: a common processing locus for micro- and macro-trade-offs?

Cognitive control processes associated with long- and short-term adjustments of human behaviour have attracted much interest recently. It is still unclear, however, whether the mechanisms underlying these adjustments share a common locus within the chain of stimulus-response processing. In order to address this issue, the present study employed a speed-accuracy instruction producing a macro-trade-off, whereas micro-trade-off was studied by means of posterror slowing in reaction time (RT). Participants performed a spatially compatible or incompatible four-stimuli-to-two-response alternative choice RT task. Reliable variations in micro-and macro-trade-off as well as effects of spatial compatibility were found in RT and error rate. Most importantly, posterror slowing was larger when instruction stressed accuracy rather than speed, an effect being independent of spatial compatibility. Because the influence of speed-accuracy instruction and posterror slowing on performance was strongest for response alternations, together present findings suggest that the mechanisms underlying micro- and macro-trade-offs have one common locus at the level of motor processing. Additional influences of macro-trade-off on premotoric processing are likely.     

The role of horizontal categorization in retroactive and proactive interference

Four paired-associate experiments with a total N of 291 participants investigated the effects of horizontal categorization on retroactive and proactive interference. (Exclusively) horizontal categorization means that unique categorical relationships hold across the A-B and A-C stimulus-response pairs of successive word lists (e.g., fruit--pear, river--Thames, in list 1; and fruit--plum, river--Wolga, in list 2). Experiment 1 found no significant amounts of interference with this type of list organization. However, strong interference arose with the same materials when the categorical structure was destroyed in Experiment 2. A third experiment contrasted two alternative explanations for these results, and Experiment 4 replicated the effect of horizontal categorization (vs. no categorical relationship) in a within-participants design. The results of the four experiments largely fit with a response competition explanation proposed by Bower, Thompson-Schill, and Tulving (1994), adapted to the within-participants designs used here. Overall, the present findings add to a body of evidence demonstrating limits to retroactive and proactive interference.     

Pavlovian conditioning in human skilled motor behavior

The role of Pavlovian contingencies in human skilled motor behavior was investigated in three experiments by means of a new conditioning preparation. In Experiment 1 the present method was shown to be appropriate for the study of associative learning. Subjects who experienced a standard delay configuration performed significantly more conditioned responses than subjects who received either backward conditioning or random pairings. Stimulus generalization was shown to be slight in two additional groups. Subsequent experiments examined conditioning with multiple conditioned stimuli (CSs). In particular, in Experiment 2 some reciprocal overshadowing was demonstrated when two conditional stimuli (tone and vibration) were compounded. Experiment 3 investigated blocking. Blocking was less than expected, however. Subjects’ perceptions of the stimuli and reaction time data suggest that a certain proportion had shifted their attention to the added element of the CS compound. Results are discussed in relation to other studies on Pavlovian learning in humans and animals, which are concerned with “stimulus selection.”