Donation requests often convey numerical information about the people in need. In two studies we investigated the effects of numeracy and presentation format on the underlying affective and cognitive mechanisms of donation decisions. In Study 1, participants were presented with information about a victim in need, either in a frequency format or in a percentage format. In Study 2, we manipulated the identifiability and number of target victims. Our results demonstrate that donations of individuals lower in numeracy were more susceptible to changes in numeric presentation format than those higher in numeracy. Importantly, the underlying mechanisms for donations differed by numeracy. Whereas the mental image of the victim influenced donation decisions of less numerate people only, the estimated impact of a donation was positively correlated with donation amounts for both more and less numerate individuals.

This paper argues that we should distinguish two different kinds of imaginative vividness: vividness of mental images and vividness of imaginative experiences. Philosophy has focussed on mental images, but distinguishing more complex vivid imaginative experiences from vivid mental images can help us understand our intuitions concerning the notion as well as the explanatory power of vividness. In particular, it can help us understand the epistemic role imagination can play on the one hand and our emotional engagement with literary fiction on the other hand.

Little is known about mental images (cognitive representations with sensory qualities) in body integrity identity disorder (BIID). This study aimed to determine whether individuals with BIID experience mental images and, if so, whether they differ to those experienced by individuals with body dysmorphic disorder (BDD) and healthy controls. A semi-structured interview on mental images and their qualities was delivered to a sample of 22 individuals with BIID and 19 with BDD, and 22 healthy controls. Both the BIID (n = 15, 68.2%) and BDD (n = 14, 73.7%) groups reported significantly more mental images than healthy controls (n = 3, 13.6%), but no differences between the two clinical groups were found. While mental images in BDD were focused on ‘flawed’ body parts, images in BIID involved the desired handicap. Mental images in BIID were experienced as less distressing and more sexually arousing compared to BDD. No further differences were found between the groups (e.g., regarding sensory multimodality, dominance of a specific body part). Although the two groups reported a similar frequency of mental images, images appear to serve different functions across conditions. Clinically, it may be necessary to target the positive mental images in BIID to improve treatment outcome.

Ethologists and comparative psychologists have found that the social behavior, discrimination learning, and especially the communicative behavior of many animals are sufficiently versatile to call into question the customary denial that animals have mental experiences comparable to our own. Many of their behavior patterns suggest that animals have mental images of objects, events, or relationships remote from the immediate stimulus situation, as well as self-awareness and intentions concerning future actions. Our behavioristic Zeitgeist has inhibited investigation of such possibilities, but reopening these long-neglected questions requires no departure from the materialistic approach to biological and behavioral science. The basic question at issue involves a comparison of those aspects of human and nonhuman brain function that sometimes lead to what we call mental experiences, at least in our own species. It seems more feasible to devise objectively verifiable tests for the existence of these general categories of mental experiences than for that of many others. While many other kinds of evidence could well be used (with appropriate caution and all possible controls) to weigh the likelihood that animals sometimes know what they are doing, the experimental use of communicative behavior seems especially promising, because the latter could serve a function analogous to human language, which provides our best evidence about the mental experiences of our fellow men.