. 71.2 5.5, 55.3 6.5 and 45.0 6.5, respectively ; there was no significant
Ž .
difference between the two latter groups t s 2.0, df s 12, P 0.05 . Indeed, the SS birds showed significantly greater INT than would be expected by chance on each of the
Ž .
test days t 2.31, df s 48, P - 0.05 . The SS video also elicited progressively more Ž
. Ž
. interest Fig. 1b with repeated exposure F
s 6.08, df s 8, P - 0.001 . The B hens
8,48
Ž .
showed more than 50 INT on day 1 t s 3.64, df s 48, P - 0.001 but thereafter, this measure did not deviate significantly from neutrality. Hens showed a neutral response to
Ž the hide until day 5 at which time INT decreased significantly t s y3.75, df s 48,
. P - 0.001 .
Our finding that INT shown by SS hens exceeded neutrality even on day 1 is not inconsistent with the observation that they showed the lowest approach scores at that
time. High INT on day 1 likely reflected the fact that the SS hens faced the front even if they were positioned at the back of the cage.
Collectively, the present results indicate that, following initial avoidance, hens became progressively more interested in the screensaver video whereas interest in the
blank television or the hide showed few deviations from neutrality. Thus, there are Ž
distinct similarities between the responses of adult hens and young chicks Jones et al., .
1996, 1998 to SS videos. The present findings also raised two questions. Firstly, would hens’ interest in SS
videos increase, be sustained at a steady level, or fall during exposure to the same image for longer than 5 days? Secondly, would stimulus change modify responsiveness? These
issues were addressed in the next experiment.
3. Experiment 2
3.1. Animals and husbandry Twenty-eight, 19-week-old ISA Brown laying hens were used. From 8 weeks of age
Ž they were housed individually in cages, measuring 60 = 50 = 77 cm width = length =
. height , in the bottom tier of a two-tier battery. Each cage was separated from adjacent
ones by metal partitions. These prevented visual contact between neighbours but, as in Experiment 1, hens housed in cages to the rear and across the aisle were visible.
Husbandry conditions were similar to those described above.
3.2. Treatments and testing The cages in the present battery system were wider than those used in the previous
experiment. Therefore, on this occasion, the hens were assigned to 14 groups of two adjacent birds to ensure that each hen received a full view of the television screen during
testing. Because there were no significant differences between hens’ responses to the blank, lit monitor and the hide in Experiment 1, the latter treatment was omitted from
the present experiment. Thus, each group was randomly assigned to one of two
Ž .
treatments seven groups per each of the SS and B treatments . The birds were exposed Ž
. for 10 minrday on 20 consecutive days to either the ‘Fish’ screensaver SS programme
Ž . or to a blank, lit television monitor B for 21 days. On day 21, the SS birds were
Ž presented with a new screensaver video ‘Doodles’, here a number of coloured wavy
lines appear on the screen at random, the screen is refreshed after a few seconds and a .
different number of lines appears . The hens were observed on each of days 1–5 and then on days 8, 11, 14, 17, 20 and
21. Each bird’s position in the cage and its head orientation were recorded from left to right every 5 s, as in Experiment 1 but this time, since there were only two birds per
group, scans were conducted at intervals of 10 rather than 15 s. Therefore, body position was recorded 60 times, and the overall approach score ranged from a minimum of 60 to
a maximum of 180. Composite scores of interest were also calculated and logit transformed as described above. The data were analysed using similar methods to those
described in Experiment 1.
3.3. Results and discussion Ž
. Ž
. Approach scores Fig. 2a were significantly higher F
s 6.96, df s 1, P - 0.03
1,12
Ž in SS than in B hens 116.3 5.3 and 107.1 4.6, back-transformed means SEMs,
. Ž
respectively . There was also a significant interaction of treatment and day F s
10,120
. 2.00, df s 10, P - 0.04 . Both SS and B hens showed lower approach scores than would
Ž .
be expected by chance on day 1 t s y4.55 and y3.77, respectively, P - 0.001 , thus suggesting initial avoidance of the stimuli, as in Experiment 1. Hens in both treatments
then showed increasing approach scores that reached neutrality on day 3. Thereafter, approach scores fell in B hens and, with the exception of days 8 and 17, remained less
Ž .
than expected by chance t 2.05, P - 0.05 whereas those of SS birds hardly deviated from neutrality, indicating neither significant approach nor avoidance. Interestingly
though, they showed much greater approach than B hens on day 21 when a new SS Ž
. image was presented t s 3.63, P - 0.001 .
Ž Treatment significantly affected overall FB behaviour
F s 6.33, df s 1, P -
1,12
. Ž
0.03 ; SS hens showed significantly less than B ones 16.8 2.3 and 23.8 2.8, .
back-transformed means SEMs, respectively . There was also a significant dayrtreat- Ž
. ment interaction F
s 2.02, df s 10, P - 0.04 . SS hens showed steadily decreas-
10,120
Ž .
Ž .
ing FB which had fallen t s y2.15, df s 120, P - 0.05 below chance 25 by day 4. After day 8, FB behaviour increased slightly but then fell significantly below
Ž .
neutrality t s y2.62, df s 120, P - 0.01 when the new SS was shown on day 21. Hens in the B treatment also showed decreasing FB for the first 3 days but thereafter
they did not deviate significantly from the neutral score of 25. In other words, FB behaviour mirrored that of approach.
Ž .
Overall, SS birds showed significantly less F
s 18.01, df s 1, P - 0.002 FO
1,12
Ž behaviour than B ones 16.4 1.9 and 26.8 2.5, back-transformed means SEMs,
. respectively . There was also a significant interaction between day and treatment
Ž .
Ž F
s 3.00, df s 10, P - 0.003 . FO was significantly less t always - y2.3,
10,120
. Ž
. df s 120, P always - 0.05 than expected by chance 25 in SS hens until day 11. It
then surpassed 25 but fell again when the birds were exposed to the new SS on day 21. Hens in the B treatment showed increasing FO which exceeded 25 as early as day
Ž .
5 and was greater than chance by day 14 t s 2.22, df s 120, P - 0.05 .
Ž . Ž .
Ž .
Fig. 2. a Approach and b interest HOqFF scores of individually caged laying hens when they were Ž .
Ž .
presented with either a blank illuminated television B or a video of a screensaver SS at the front of their cages for 10 minrday on each of 21 and 20 consecutive days, respectively. The SS birds were exposed to a
different SS on day 21. Interest scores are expressed as percentages of the scanning observations made. Back-transformed meansSE are based on seven groups of two hens per treatment.
Ž .
Ž .
Treatment also affected overall interest INT scores Fig. 2b ; these were signifi- Ž
cantly greater in SS than in B hens 58.5 2.9 and 37.4 2.8, back-transformed .
Ž .
means SEMs , respectively F
s 37.54, df s 1, P - 0.001 . There was also a
1,12
Ž .
significant interaction between treatment and time F s 8.45, df s 10, P - 0.001 .
10,120
The SS hens showed significantly greater interest than would be expected by chance on Ž
. Ž
. each of days 3 t s 2.39, df s 120, P - 0.02 , 4 t s 3.39, df s 120, P - 0.001 , 5
Ž .
Ž .
t s 3.65, df s 120, P - 0.001 , and 8 t s 2.71, df s 120, P - 0.01 . A numerical
trend towards greater interest values than neutrality on day 11 failed to reach signifi- Ž
. cance t s 0.81, df s 120, P 0.2 and the scores fell slightly below the 50 level on
days 14, 17 and 20. However, positive interest, i.e., greater than neutrality, was re-established on day 21 when the SS birds were presented with the new SS image
Ž .
t s 3.87, P - 0.001 . Interest was slightly but non-significantly greater than neutrality in B hens on days 2 and 3 but it waned rapidly thereafter; indeed from day 11 onwards
Ž .
the scores fell significantly below the 50 level P always - 0.01 . Collectively, these results indicate that the birds were initially wary of both the B and
SS stimuli. SS hens soon began to show significant interest in the video image which was sustained till at least day 8. Interest then waned with continued daily exposure but it
was fully reinstated when a new SS image was presented. Conversely, not only did a blank, lit television screen fail to elicit significant interest at any time during the 21-day
observation period but the scores also consistently fell below neutrality from day 5 onwards.
4. General discussion
