Inanimate Stimulus Research Articles

The effect of automatic imitation in serial movements with different effectors.

Individuals often imitate the postures or gestures of others in everyday life, without even being aware. This behavioral tendency is known as "automatic imitation" in laboratory settings and is thought to play a crucial role in social interactions. Previous studies have shown that the perception of a simple finger movement activates a shared representation of the observed and executed movements, which then elicits automatic imitation. However, relatively few studies have examined whether automatic imitation is limited to simple single-finger movements or whether it can be produced using a different automatic imitation paradigm with more complex sequential movements. Therefore, this study conducted three experiments in which participants observed the sequential movements of a model and then executed a compatible (similar) action or an incompatible (different) action involving the hand or foot in response to number cues that indicated the sequence for moving their hands or feet. The delay to onset of participants' initial hand or foot movements was calculated. Participants consistently executed compatible actions faster than incompatible actions. In particular, the results showed an imitative compatibility effect with a human stimulus but not an inanimate stimulus. These results demonstrate that automatic imitation occurs during more complex movements that require memory.

Fine-grained stimulus representations in body selective areas of human occipito-temporal cortex

Neurophysiological and functional imaging studies have investigated the representation of animate and inanimate stimulus classes in monkey inferior temporal (IT) and human occipito-temporal cortex (OTC). These studies proposed a distributed representation of stimulus categories across IT and OTC and at the same time highlighted category specific modules for the processing of bodies, faces and objects. Here, we investigated whether the stimulus representation within the extrastriate (EBA) and the fusiform (FBA) body areas differed from the representation across OTC. To address this question, we performed an event-related fMRI experiment, evaluating the pattern of activation elicited by 200 individual stimuli that had already been extensively tested in our earlier monkey imaging and single cell studies (Popivanov et al., 2012, 2014). The set contained achromatic images of headless monkey and human bodies, two sets of man-made objects, monkey and human faces, four-legged mammals, birds, fruits, and sculptures. The fMRI response patterns within EBA and FBA primarily distinguished bodies from non-body stimuli, with subtle differences between the areas. However, despite responding on average stronger to bodies than to other categories, classification performance for preferred and non-preferred categories was comparable. OTC primarily distinguished animate from inanimate stimuli. However, cluster analysis revealed a much more fine-grained representation with several homogeneous clusters consisting entirely of stimuli of individual categories. Overall, our data suggest that category representation varies with location within OTC. Nevertheless, body modules contain information to discriminate also non-preferred stimuli and show an increasing specificity in a posterior to anterior gradient.

Sensory determinants of agonistic interactions in the red-backed salamander, Plethodon cinereus

Many animals use and react to multimodal signals — signals that occur in more than one sensory modality. This study focused on the respective roles of vision, chemoreception, and their possible interaction in determining agonistic responses of the red-backed salamander, Plethodon cinereus. The use of a computer display allowed separate or combined presentation of visual and chemical cues. A cue isolation experiment using adult male and juvenile salamanders showed that both visual and chemical cues from unfamiliar male conspecifics could increase aggressive displays. Submissive displays were only increased in juveniles, and specifically by the visual cue. The rate of chemoinvestigation of the substrate was increased only by chemical cues in adults, whereas both chemical and visual cues increased this behaviour in juveniles. Chemoinvestigation appears, thus, more dependent on sensory input in juvenile salamanders. A follow-up experiment comparing responses to visual cues of different animals (conspecific salamander, heterospecific salamander and earthworm) or an inanimate object (wood stick) showed that exploratory behaviour was higher in the presence of the inanimate object stimulus. The heterospecific salamander stimulus produced strong submissive and escape responses, while the conspecific salamander stimulus promoted aggressive displays. Finally, the earthworm stimulus increased both aggressive and submissive behaviours at intermediate levels when compared to salamander cues. These specific combinations of agonistic and exploratory responses to each stimulus suggest that salamanders could discriminate the cues visually. This study sheds some light on how information from different sensory modalities guides social behaviour at different life stages in a salamander.

Anticipation of Action Intentions in Autism Spectrum Disorder

We investigated whether individuals with a mild form of autism spectrum disorder (ASD) are influenced by an actor's gaze direction when anticipating how an observed action will continue in the immediate future. Participants observed a head rotate towards them, while the gaze direction was either leading, or lagging behind, rotation. They also observed identical rotations of a cylinder containing the geometrical equivalent of the gaze manipulation. The control group was influenced by the gaze manipulations for the animate but not the inanimate stimulus. The ASD group did not discriminate between the stimuli, showing a similar influence for both. This suggests that the ASD responses in the animate condition were biased by the low-level directional features of the eyes rather than by the conveyed intentions.

The effect of a gradual separation from the mother on later behavioral, immune and endocrine alterations in artificially reared lambs

The aim of the experiment was to compare the welfare and weight gains of artificially reared lambs when gradually separated from their mothers or separated from them early and immediately or gradually moved from maternal to reconstituted milk. Forty Comisana lambs were assigned to a control dam-suckled (DS) group and three test groups of 10 each. The lambs in the GRAD group were gradually separated from their dams reducing the time spent with the mothers by degrees over 10 days, while the lambs in the substitute (SUB) and EM groups were abruptly removed from their dams 24–30h post-partum. After separation, the lambs in the SUB group were provided with a milk substitute, while the lambs in the EM group were subjected to a gradual transition from ewe milk to the milk substitute over 10 days. At 12 and 32 days of age all the lambs underwent open-filed tests, during which their behavioral responses to isolation and to an inanimate stimulus—a hobby horse—were measured. In addition, blood samples were collected immediately before the isolation test, and then 10 and 60min after to evaluate cortisol concentrations. Cell-mediated immune responses in vivo to phytohemagglutinin (PHA) injection were evaluated at 7, 21 and 35 days of age, while antibody titers against chicken egg albumin (OVA) were determined at 2, 10, 20, 30 and 42 days of age. The weight gains of the lambs were also recorded weekly. When isolated in a novel environment, the GRAD lambs performed less frequent climbing attempts (P<0.05) than did the DS lambs. After the introduction of a hobby horse, the GRAD lambs displayed a longer latency time to move than did the DS, SUB (P<0.01) and EM lambs (P<0.05), and a shorter duration of movement than the DS lambs (P<0.05). The lambs in the GRAD group showed a higher cortisol release and a lower cell-mediated immune response than the three other groups; their antibody titers were also lower than those of the EM and SUB lambs. The GRAD lambs exhibited a lower growth rate than the animals in the DS (P<0.01), EM (P<0.05) and SUB groups (P<0.001). Our results suggest that a gradual separation from the mothers adversely affects behavioral, immune and endocrine responses of artificially reared lambs.

Early feather pecking as a form of social exploration: the effect of group stability on feather pecking and tonic immobility in domestic chicks

In two lines of White Leghorns that differ in their propensity to feather peck, feather pecking was already present 1 day after hatching. A significant line difference developed within 3 days and this difference remained in the following weeks. There was no clear relationship between feather pecking and ground pecking, instead feather pecking was associated with other socially orientated pecks. When chicks were confronted with feathers as an inanimate stimulus pecking at these feathers did not reflect pecking in a social context. These results suggest that feather pecking has an underlying social component, rather than being a redirected behaviour. To test the influence of social factors on feather pecking, chicks from the high feather pecking line were subjected to regular rehousing or regular rehousing plus confrontation with unfamiliar peers. Gentle feather pecking increased significantly in groups that were rehoused with unfamiliar peers. Directly after confrontation chicks displayed a preference in the total number of pecks toward these unfamiliar birds. Gentle feather pecking as a separate pecking orientation showed a similar trend. Increased righting times in a tonic immobility test were recorded in the experimental groups, hence frequent confrontation with unfamiliar peers may be experienced by chicks as stressful, which is consistent with the hypothesis that stress mediates the expression of feather pecking. In contrast to the dominant hypotheses in the field, we argue that gentle feather pecking at an early age plays an important role in the building (social exploration) and maintenance of social relationships between chicks.

Effects of animate vs. inanimate stimuli on curiosity behavior in greater galago and slow loris

Captive prosimians housed in a semi-natural laboratory environment were exposed to novel stimuli, both animate (cat, snake) and inanimate (empty box). Observations were made by means of closed circuit TV. Animate stimuli elicited considerably more interest (about 42% of a test session) than the inanimate stimulus (about 12% of the test session). The more vulnerable species, the slow loris, displayed as much curiosity as the less vulnerable species, the greater galago; but, in the presence of live stimuli, lorises were more cautious. They moved slowly and silently, employed contact as a mode of investigation significantly less often than galagos, spent significantly less time than galagos investigating from within 3 ft, took significantly longer than galagos to make their first approaches to within the 3 ft zone, and, once there, stayed for significantly shorter visits than galagos. The data demonstrate: (1) that prosimians are highly responsive to novelty if the stimuli are appropriate; and (2) that it is important to take into account not just whether animals investigate but also how they investigate.

Altering Sharing Behaviors Through Stimulus Control

The present study employed an ABA design to investigate relationships between play materials and sharing behaviors in four groups of elementary school-age children. During the first baseline condition, the children were provided with a restricted number of play materials in order to facilitate sharing among the youngsters. During the second phase, when each child was supplied with all play materials, sharing behaviors were eliminated in all groups. With return to baseline condition (i.e., limited access to sharing materials), sharing interactions were documented again in the groups of children. Data from this investigation clearly indicate that inanimate stimulus properties of settings (i.e., play materials) have the potential to enhance or impede sharing behaviors in youngsters.

Social grouping cannot account for cerebral effects of enriched environments

Several experiments were conducted to test whether, as suggested by Welch et al. in this journal 20, mere group living (social stimulation) can account for the significant differences in measures of brain anatomy and brain chemistry that develop between rodents housed in groups in enriched environments and rodents housed singly in restricted environments; the alternative hypothesis was that features of the inanimate environment can significantly affect brain measures of animals living in a social group. Groups of 12 male rats were assigned for 30 days to several types of environment: (a) large cage without stimulus objects, (b) large cage containing varied stimulus objects, (c) large cage containing a maze whose pattern of barriers was changed daily, and (d) a seminatural outdoor environment; in each experiment, littermates of rats in the social conditions were housed in isolation in small colony cages. At the end of the 30-day period, measures were taken of weights of brain regions, RNA and DNA contents of regions of cerebral cortex, and acetylcholinesterase activities of brain regions. Although the number of rats housed together was constant for conditions a−d and cage size was constant for conditions a−c, the magnitudes of the cerebral measures varied significantly as a function of the inanimate stimulus conditions. The differences from isolation-housed littermates was greatest in condition d and smallest in condition a. Thus, social grouping alone is inadequate to explain the cerebral effects of enriched environments and the inanimate stimulus conditions must be taken into account.

Scopolamine: Effects on fear or defense responses in the rat

In previous research scopolamine reduced fear or defense responses of rats to a cat, and removal of the rats' olfactory bulbs had the same effect. This suggested that scopolamine might have affected defense responses by blocking olfactory perception of the stimulus cat. The present experiments studied this possibility and explored further the effects of scopolamine on defense responses of the hooded rat. In Experiments 1 rats treated with scopolamine were found to be responsive to olfactory cues from a cat. When cat smell, but not a cat, was present in the apparatus, scopolamine-treated rats showed a large and significant suppression of food consumption. In Experiment 2 the effects of scopolamine on defense responses were shown to be generalizable to an inanimate stimulus, mechanical robot. Scopolamine caused significantly less freezing and avoidance and significantly shorter latencies to drink in the presence of the robot. One of the primary findings of the present research is that scopolamine has now been shown to reduce the defensive response of freezing in a variety of stimulus situations. This finding was thought to have important implications for the literature relating anticholinergic drugs and avoidance behavior.

The relative effectiveness of an inanimate stimulus and a live surrogate during imprinting in Japanese quail, Coturnix coturnix japonica.

It has been demonstrated repeatedly that stimuli vary in their effectiveness in eliciting and maintaining imprinting. Agreement has not been reached, however, with regard to the ideal imprinting model for laboratory studies. This situation is in part a result of the inability to replicate precisely natural parameters in the laboratory. Thus laboratory results are often inconsistent with field research. In order to develop a more biologically appropriate imprinting stimulus, a live Japanese quail hen was conditioned to serve as an imprinting object. An imprinting study was then performed to assess the dimensions of effectiveness of the live model. Comparisons between the live model and a decoy yielded different patterns of imprinting in young Japanese quail.

Early aggressive responses in domestic chicks

The frequency and persistence of early aggressive responses were studied in isolate and paired white leghorn chicks at 1 2 , 1 1 2 , 2 1 2 and 4 1 2 days of age, by presenting an inanimate stimulus object 44 times at consecutive two-min intervals. Initial threat frequencies were greater in the older chicks. With repeated presentation of the stimulus, there was an initial tendency for threats to increase, especially in the older age classes. In the 4 1 2 -day chicks, this initial increase in threats was associated with a corresponding decrease in competing withdrawal responses. With subsequent presentations, threats declined to low or negligible levels in all groups tested. Aggressive pecks declined at a rate similar to threats, whereas non-aggressive pecks increased. It is concluded that aggressive responses in domestic chicks increase during the first few days after hatching, and are subject to rapid reduction with repeated presentation of the stimulus. The possibility is discussed that the onset of aggression under natural conditions is delayed until the second week of age because repeated exposure to brood mates renders them less effective as eliciting stimuli and retards development of the underlying mechanisms.