On the nature of action-sentence compatibility effects.

Strong versions of the embodied account of language processing propose that comprehension depends on the mental simulation of sensorimotor experiences conveyed by linguistic meaning. Primary support in favor of this view is based on demonstrations of processing advantages for compatibility between an action implied by sentence content and concurrent sensorimotor processing. Although these effects have been reported across a variety of contexts, various attempts to reproduce these results, both through direct replication and conceptual extension, have not been successful. We present a series of experiments that examine the viability of previous methods used to obtain compatibility effects and the validity of the typical interpretation of such effects as evidence for mental simulation of described actions. Our findings add to the growing body of evidence that compatibility between sentence content and sensorimotor processing does not produce robust compatibility effects. Further, our findings suggest the data obtained from some studies that have been successful in generating compatibility effects can be accounted for without appealing to the notion that these effects are due to the simulation of actions implied by the meaning of a sentence. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Components of competitor priming in task switching.

Executing an action in response to a stimulus is thought to result in the creation of an event code that integrates stimulus and action features (Allport, 1987; Hommel in Visual Cognition 5: 183-216, 1998). When switching between tasks, competitor priming occurs if a distractor stimulus cues the retrieval of a previously established event code in which that distractor is bound to a competing task, creating a source of interference with the current task whereby the observer is encouraged to apply the competing task to the distractor. We propose a second aspect of competitor priming: the misapplication of the retrieved competing task to the target stimulus. We report two task-switching experiments in which tasks applied to picture-word compound stimuli were manipulated to create conditions in which this second aspect of competitor priming could be revealed and distinguished from other sources of task- and stimulus-based priming. A substantial increase in competitor priming was observed when subjects switched between tasks that required very different processing operations and the competing task was highly relevant to the target stimulus. These results are consistent with our claim that competitor priming can result from applying the competing task either to the distractor that cued it or to the target stimulus.

Environmentally relevant stressors alter memory formation in the pond snail Lymnaea.

Stress alters adaptive behaviours such as learning and memory. Stressors can either enhance or diminish learning, memory formation and/or memory recall. We focus attention here on how environmentally relevant stressors alter learning, memory and forgetting in the pond snail, Lymnaea stagnalis. Operant conditioning of aerial respiration causes associative learning that may lead to long-term memory (LTM) formation. However, individual ecologically relevant stressors, combinations of stressors, and bio-active substances can alter whether or not learning occurs or memory forms. While the behavioural memory phenotype may be similar as a result of exposure to different stressors, how each stressor alters memory formation may occur differently. In addition, when a combination of stressors are presented it is difficult to predict ahead of time what the outcome will be regarding memory formation. Thus, how combinations of stressors act is an emergent property of how the snail perceives the stressors.

Combining stressors that individually impede long-term memory blocks all memory processes.

The effects of stress on memory are typically assessed individually; however, in reality different stressors are often experienced simultaneously. Here we determined the effect that two environmentally relevant stressors, crowding and low calcium availability, have on memory and neural activity following operant conditioning of aerial respiration in the pond snail, Lymnaea stagnalis. We measured aerial breathing behaviour and activity of a neuron necessary for memory formation, right pedal dorsal 1 (RPeD1), in the central pattern generator (CPG) that drives aerial respiration in untrained animals, and assessed how these traits changed following training. In naïve animals both crowding and combined stressors significantly depressed burst activity in RPeD1 which correlated with a depression in aerial breathing behaviour, whereas low calcium availability had no effect on RPeD1 activity. Following training, changes in burst activity in RPeD1 correlated with behavioural changes, decreasing relative to their naïve state at 3 h and 24 h in control conditions when both intermediate-term memory (ITM: 3 h) and long-term memory (LTM: 24 h) are formed, at 3 h but not 24 h when exposed to individual stressors when only ITM is formed, and did not change in combined stressors (i.e. when no memory is formed). Additionally, we also found that Lymnaea formed short-term memory (STM: 10 min) in the presence of individual stressors or under control conditions, but failed to do so in the presence of combined stressors. Our data demonstrate that by combining stressors that individually block LTM only we can block all memory processes. Therefore the effects of two stressors with similar individual affects on memory phenotype may be additive when experienced in combination.

What's hot: the enhancing effects of thermal stress on long-term memory formation in Lymnaea stagnalis.

The pond snail, Lymnaea stagnalis, naturally inhabits slow flowing, shallow and stagnant environments in the northern temperate zone. Consequently, it will experience wide temperature fluctuations dependent on prevailing weather conditions. We hypothesize that periods of warming act as a thermal stressor to alter memory formation. Snails were exposed to an acute 1 h period of 30°C pond water and we determined how memory formation following operant conditioning of aerial respiration was affected. In the snails used here (Dutch strain), a single 0.5 h training session (TS) results in intermediate-term (3 h) but not long-term memory (LTM). Applying the thermal stressor during training caused memory enhancement (i.e. LTM lasting 24 h). However, the breathing rate also increased in warm water, which might explain the enhanced memory. Therefore, we applied the thermal stressor (1 h at 30°C) up to 4 h before or 1 h after training. This did not alter baseline breathing rate during the period when snails would experience training. However, the thermal stressor whether experienced prior to or following the single TS, resulted in an enhanced memory that persisted up to 48h (i.e. LTM). We conclude that memory enhancement is due to the stress associated with the thermal stimulus.