Discriminability and memorability are two aspects of receiver psychology; a component of sensory processing that directly precedes the receiver response. Endler (1993) emphasizes that the receiver is an overlooked player and he provides a framework to better understand the role that psychology plays in signal efficacy. Prior to discriminability and memorability, an organism must detect a signal. Like discriminability, detectability is more heavily involved in signal efficacy and sensory exploitation. Memorability is affected by efficacy and sensory exploitation as well but involves more cognitive elements (Guilford and Dawkins 1991). Certain receivers can discriminate between group members using cues and/or signals during conflicts and use this information to make social decisions in the future (Sima et al. 2017).
Miriam Jennifer Sima et al. (2017) demonstrated that feeding conflicts in carrion crows influence post-feeding behaviors, such as affiliation and reconciliation. This would suggest that carrion crows are able to discriminate between flock members during feeding and after feeding phases, and remember competitors, third party offenders, and third party victims from feeding phase conflicts (Sima et al. 2017). Observed signals during feeding conflicts were contact aggression (peck, fight) and in non-contact aggression (displacement, chase). Sima et al. (2017) split the agonistic data into two sensory modalities: tactile (peck, fight) and visual (displacement, chase). Then a correlation was calculated between agonistic behaviors expressed in the feeding phase and affiliate and reconciliation behaviors in the after-feeding phase.
Sima et al. (2017) predicted that there would be third party affiliation between former victims of aggression and a third party (not the aggressor) and that there would be reconciliation between aggressors and victims of aggression. Affiliate and reconciliatory behaviors match the same criteria, allo-preening, food sharing, or contact sit, but are between different players within the conflict. Sima et al. (2017) also predicted that victims of contact aggression would receive stronger affiliate/reconciliatory behaviors in the after-feeding phase (allo-preening>food sharing>contact sitting). Their data supported each of these predictions. Former victims of aggression almost always received affiliation or reconciliation, former victims of contact aggression received reconciliation or affiliation significantly more than victims of non-contact aggression, all victims of aggression received affiliation significantly more than reconciliation, and there was a trend between whether or not an aggression involved contact and affiliate /reconciliatory behaviors. Victims of contact aggression received allo-preening significantly more than victims of non-contact aggression (Sima et al. 2017).
These results suggest that carrion crows may use tactile and visual signals and/or cues during threat displays during feeding to make post-feeding decisions. It also supports that carrion crows can discriminate between flock members and remember previous conflicts. The most interesting finding is that feeding conflicts are reciprocated with post-feeding cooperation. It is possible that offenders reconcile and third parties affiliate with victims to receive benefits in future conflicts. If carrion crows remember a group member as a third party affiliate then they may treat them with less aggression during feeding. If a carrion crow remembers a group member that was a contact aggressor, then it might not want to compete with that crow in the future. Reconciliation could then enhance memorability by reinforcing original memory.
