A New Standardized Stimulus Set for Studying Need-of-Help Recognition (NeoHelp)

This article presents the NeoHelp visual stimulus set created to facilitate investigation of need-of-help recognition with clinical and normative populations of different ages, including children. Need-of-help recognition is one aspect of socioemotional development and a necessary precondition for active helping. The NeoHelp consists of picture pairs showing everyday situations: The first item in a pair depicts a child needing help to achieve a goal; the second one shows the child achieving the goal. Pictures of birds in analogue situations are also included. These control stimuli enable implementation of a human-animal categorization task which serves to separate behavioral correlates specific to need-of-help recognition from general differentiation processes. It is a concern in experimental research to ensure that results do not relate to systematic perceptual differences when comparing responses to categories of different content. Therefore, we not only derived the NeoHelp-pictures within a pair from one another by altering as little as possible, but also assessed their perceptual similarity empirically. We show that NeoHelp-picture pairs are very similar regarding low-level perceptual properties across content categories. We obtained data from 60 children in a broad age range (4 to 13 years) for three different paradigms, in order to assess whether the intended categorization and differentiation could be observed reliably in a normative population. Our results demonstrate that children can differentiate the pictures' content regarding both need-of-help category as well as species as intended in spite of the high perceptual similarities. We provide standard response characteristics (hit rates and response times) that are useful for future selection of stimuli and comparison of results across studies. We show that task requirements coherently determine which aspects of the pictures influence response characteristics. Thus, we present NeoHelp, the first open-access standardized visual stimuli set for investigation of need-of-help recognition and invite researchers to use and extend it.

Green shading indicates identical effects; orange shading indicates differences in effects due to non-significance in one of the picture-size subgroups, but an identical direction of absolute differences; red shading indicates differences in effects including their direction.

Comparison of participant populations in both picture-size subgroups
The total number of children included for analysis, distribution of gender and pet-ownership for the total sample, as well as the picture-size-subgroups are presented in Table S2.Systematic differences in demographic variables between picture-size subgroups were explored using a Wilcoxon rank sum test and exact binomial tests (π = estimated proportion of hits in the other subgroup). Age, gender and pet-ownership were not different between picture-size subgroups, W = 55, p = .05, p = .79 and p = .83, respectively (for percentages compare rows of Table S2).Thus, no systematic differences between picture size subgroup were observed for any of the demographic variables considered.

Ambiguous situations
Figure S1 shows estimated probabilities of success for each situation and paradigm when presented small. In sum, picture-size did not considerably influence the fact that pictures of almost all depicted situations (13 out of 15, marked with green outlines in all columns of Fig. S1 A-B) were unambiguously identifiable as depicting need-of-help (NoH). Highly similar results of binomial tests of hit rates for small-and large-picture subgroups (see Table S1) substantiate the conclusion that children perceived the difference between no-NoH-and NoH-depictions in all but two situations, regardless of whether they saw larger or smaller variations of the stimuli. Moreover, all three situations that were only correctly displayed in smaller size were unambiguous regarding need-of-help as well as human-/animal content in all three paradigms (see rightmost three bars in Fig. S1 A-C).

Changes in hit rates and RTs according to task demands
Detailed results of the ANOVA conducted for the small-picture subgroup are given in Table   S3. As opposed to the analysis of the large-picture subgroup the mean hit rates of the small picture subgroup did not differ significantly between P1-bird (bird-human-distinction required) and P3-help-side. However, the remaining differences pointed into the same direction: P2-help was the paradigm with lowest accuracy. The pattern revealed by the main effect of paradigm with regard to RTs, (P1-bird <P2-help <P3-help-side) emerged in both picture size subgroups alike and thus irrespective of picture size. As can be seen in Table S1 differences in effects of task demands between picture-size subgroups were restricted to the absence of one post-hoc difference.

Effects of stimulus content on hit rates and RTs
The detailed results of the ANOVAs considering S1-bird for both, hit rates and RTs are given in Table S4.The pattern of effects on RTs was the same in large-and small-picture subgroups (see Table S1). Regarding hit rates, the same factor bird-depiction yielded the only significant effect in both picture-size subgroups while no interactions were found in either picture-size subgroup. However, the main effect of bird-depiction had opposite directions for the large-picture and small-picture subgroups. Birds were categorized more accurately in the large-picture subgroup whereas humans were more accurately categorized in the small-picture subgroup. This inversion of bird-depiction's main effect might arise due to differences in task difficulty according to picture-size: Hit rates were generally higher in the large-picture subgroup and on average above 92%, indicating that a ceiling effect could have played a role in changing the direction of the effect of bird-depiction on hit rates.
The detailed results of the ANOVAs considering S2-help for both, hit rates and RTs are given in Table S5. Mean RTs and hit rates for the 14 situations remaining in analysis are shown in Figure S2. We did not find pronounced differences in main effects between the small-picture and large-picture subgroups in P2-help.  Hit rates (bars) and mean RTs (dots) were calculated across all variations of a given situation.
White triangles mark significant differences in hit rates compared to the situation "table_chair", their number corresponding to p-values of post-hoc Tukey HSD tests (one: p < .05, three: p < .001). Error bars represent SEM.
Divergences in effect patterns regarding hit rates and RTs were restricted to the absence of some significant interactions and one main effect in the small picture size subgroup (see Table   S1), which was also considerably smaller in sample size (N = 22) than the large-picture subgroup (N = 60). Thus, divergences in effect patterns between picture-size subgroups are likely due to the smaller sample size, since all effects for both pictures size-subgroups pointed in the same direction, including the pattern revealed by the interaction of NoH-depiction and bird-depiction (see Table S6). Note. NoH = need-of-help. Numbers in brackets represent SDs.
The detailed results of the ANOVAs considering S3-help-side for both, hit rates and RTs are given in Table S7. Mean RTs and hit rates for the 14 situations remaining in analysis are shown in Figure S3.Effect patterns found in the large and small picture-size subgroups in paradigmP3-help were highly similar (see Table S1). Given that considerably fewer children (N = 22) were assigned to the small picture-size subgroup and that the only differences were restricted to a lack of significant main effects and interactions in this subgroup, it is likely that content-related picture properties' influences on response characteristics in P3-help-side were independent of picture size. What is more, we also found that differences between situations were similar in both subgroups, the only discrepancy being again that some differences did not reach significance in the smaller subgroup.