Introduction - Semantic Acquisition Games: Harnessing Manpower for Creating Semantics - page 3

effectively being deployed to narrow problems, where enough training data is
available or when they can be supervised by humans effectively.
The crowdsourcing games established themselves over the last decade as powerful
means of harnessing of the human computational capacity and also as a research
field [ 7 , 19 , 20 ]. They take the advantage of the fact that computer game players do
non-trivial thinking during gaming in order to win: they formulate strategies, evaluate
complex situations, make decisions or consume and process the multimedia content.
Crowdsourcing games aim to harness this actual brain power in their favor. Using
a specially designed game rules, they align the game process and winning conditions
with solving a human intelligence task —a task that is easy to be solved by a human
being, but hard or impossible to be done by a machine [ 5 , 10 , 15 ]. Crowdsourcing
games record played games and use these logs to extract portions of knowledge
produced by the players, further cross-validating them in order to retrieve problem
solutions and useful virtual artifacts.
Many of the crowdsourcing games are used for (web) semantics acquisition
tasks—we then call them semantics acquisition games (SAGs). These tasks pre-
dominately include:

￿ Acquisition of multimedia annotations. Here, the games are designed in a way

that players need to provide information about multimedia in order to win [ 17 ].
A prominent example is the ESP Game , where two players collect points when
they match on a particular textual description of a given image [ 5 , 20 ].

￿

Acquisition of text annotations. Some SAGs were devised for tasks in natural
language processing, namely the co-reference matching [ 3 , 4 ].

￿ Acquisition of domain models. Variety of games was designed for ontology

construction, like common fact collecting [ 20 ], ontology expansion [ 7 , 10 ]or
ontology linking [ 19 ].

Altogether, the semantics acquisition games represent an attractive research field
as they may be potentially used for many human intelligence tasks. But apart from
fulfilling individual purposes, the SAGs impose also some general design challenges
that have not yet been solved: lack of effective validation of created artifacts (i.e. the
“useful” products of the game), anti-cheating issues, lack of popularity and attrac-
tiveness [ 7 , 20 ]. Today SAGs are being created ad-hoc for each human intelligence
task, and there is no generic methodology for straightforward transformation of
a problem to a game, which leaves very interesting research questions open.

1.1 Challenges and Goals

Our work is aligned around the domain of human oriented approaches to semantics
acquisition: the semantics acquisition games (SAGs) which are established as a part
of crowdsourcing (resp. human computation) research field. From the semantics
acquisition standpoint, there are several, still-open challenges.