User-centered design is an iterative design process in which designers focus on the users and their needs in each phase of the design process. UCD calls for involving users throughout the design process via a variety of research and design techniques so as to create highly usable and accessible products for them. https://www.interaction-design.org/literature/topics/user-centered-design is a useful resource. 

Human-centred and user-centred design are closely related terms. User-centred design has its roots in ergonomics and HCI (human computer interaction), and is closely tied to digital UX (user experience) contexts where the person performing a task is known and the process therefore tends to focus on optimising the characteristics of the product, system or service based on preconceived plans. In the context of software or hardware, the person may also consider themselves to be a user, whereas in other cases, for instance, physical objects like door knobs or light switches, ‘user’ feels like a bit of a stretch. Technically accurate, just a little clinical and detached.

Human-centred design is broader, in that in many contexts, a design outcome may have multiple different types of user (or stakeholder), so focussing on one may ignore the needs of others (Bowen, 2009, p.27). (In addition, where a lightswitch user would sound a bit odd, to call someone viewing a poster ‘a user’ would be nonsensical).

Hence, HCD covers a broader group (and UCD may be considered as a subset of it). HCD also suggests a shift towards techniques which communicate, interact, empathise and stimulate the people involved (Giacomin, 2014), obtaining an understanding of requirements (needs, wants, experiences) which often transcends that which the people themselves would have been able to articulate prior (Giacomin, 2014).

So far, so product-focussed. But, HCD has also been considered more than this too: Richard Buchanan (2001) argues ‘that its primary purpose is in supporting human dignity’ (Bowen, 2009, p.27). In this project, HCD will be employed as part of a design thinking approach to the problem(s) and question(s) that arise. Rough prototyping, testing, reflecting and iterating will be undertaken in as many situations as possible. Ideally, ‘users’ will be identified to participate in the process (which may necessitate finding representatives of ‘publics’ that are the targets of research). Using UCD tools such as the development of personas (composite people based on research developed to represent a target group) might help target science communication, or act as a reflexive tool for scientist-communicators to ‘design’ their engagement activities for.