Ž . Ž
. blank, lit television B was again used a control. An unfamiliar video Doodles was presented to
the SS birds on day 21 to determine the effects of stimulus change. After avoiding the stimuli upon their first presentation, both SS and B birds achieved neutrality by day 3. Approach scores
then fell in B birds but rarely deviated from neutrality in SS ones. The SS video attracted markedly more interest than did the blank screen. On this occasion, SS hens showed significantly
greater interest than would be expected by chance as early as the third presentation and this was still evident upon the eighth presentation; thereafter it waned gradually. However, interest was
reinstated fully when the unfamiliar SS image was shown on day 21. The present findings clearly demonstrate that abstract video images, presented in front of the home cage for 10 min on
consecutive days, reliably attracted and sustained the interest of individually housed laying hens for as long as 8 days. These results are consistent with those obtained when chicks were
repeatedly exposed to similar screensaver videos, i.e., this phenomenon is not dependent on the stage of development. Our results also confirm the importance of considering the environment
outside as well as inside the cage in future environmental enrichment programmes. q 2000 Elsevier Science B.V. All rights reserved.
Keywords: Chicken-housing; Interest; Video stimulation; Laying hens; Environmental enrichment
1. Introduction
Ž The domestic chicken has a large, well-developed visual system King-Smith, 1971;
. Rogers, 1995 and visual stimulation plays a major role in regulating behaviours as
varied as feeding, imprinting, aggression, territoriality, social recognition, and mate Ž
. choice Fischer, 1975; Rogers, 1995 .
There is growing evidence that chickens can process information from televised images and show appropriate responses. Indeed, this medium is being increasingly used
as a means of presenting tightly controlled visual stimuli in poultry behaviour research. Ž
For example, video images of feeding Keeling and Hurnik, 1993; McQuoid and Galef, .
Ž .
1993, 1994 and dustbathing Lundberg and Keeling, 1997 chickens elicited similar behaviour in viewing hens. Chickens also delayed feeding when video images of
Ž .
threatening conspecifics were being shown D’Eath and Dawkins, 1996
and they responded to televised images of aerial and ground predators with appropriate anti-pre-
Ž .
dator behaviour Evans and Marler, 1991, 1992; Evans et al., 1993 . Chicks also regulated their behaviour in response to biologically neutral video
images, i.e., ones that bore no connotations of predation, feeding or social attraction. Thus, when either individually or socially housed chicks received repeated daily
exposure from 1 to 9 or to 11 days of age in their home cages to a blank, illuminated Ž .
Ž .
television screen B or to a video image of a computer screensaver SS they showed Ž
. progressively greater approach Jones et al., 1996, 1998 . This trend was much more
pronounced in SS than B chicks, though attraction to SS appeared to plateau after 6 days in grouped chicks.
It is widely recognized that young birds reared in the absence of a mother or siblings Ž
may become imprinted on any of a wide range of inanimate stimuli Bolhuis, 1991; van .
Kampen, 1996 . This may at least partially explain the strong attraction to SS videos Ž
. shown by individually caged chicks Jones et al., 1996 although the similar responses
Ž .
of birds reared in trios Jones et al., 1998 suggested that social housing, and the consequent likelihood of filial imprinting, did not prevent attraction and attachment to
the abstract videos. However, because chickens are thought to show strong age-depen- Ž
dent changes in exploratory behaviour Workman and Andrew, 1989; Vallortigara et al., .
1997 , it is conceivable that their attraction to and interest in biologically neutral video images might also vary substantially with age. Therefore, the present study was designed
to establish whether or not the home cage responses of young chicks to repeated presentations of screensaver videos were paralleled in adult laying hens. In Experiment
1, we compared the responses of individually caged hens when they were presented with
Ž .
either the video image of a computer screensaver stimulus SS, Fish , a blank,
Ž . Ž .
illuminated television monitor B , or a hide H in front of their battery cage for brief periods on each of 5 consecutive days. The exposure period was extended to 20 days in
Experiment 2, which also examined the effects of stimulus change by introducing a new Ž
. video image Doodles on day 21.
2. Experiment 1
